Woman tying bikini bottoms

Swimwear makers, listen up! You know the details matter when it comes to creating a beautiful, comfortable, and durable swimsuit. One of the factors that can make a significant difference in the quality and fit of a swimsuit is the use of high-quality swimwear notions.

Swimwear notions are the small, often overlooked, components that go into the sewing of swimsuits and bikinis. Elastic, clasps, o-rings, hooks, sliders, stoppers and all these other small elements play a crucial role in ensuring swimsuits look and feel great. 

In this comprehensive guide, we'll walk through everything you need to know about swimwear notions, and we'll go over the various different types, materials and their functions.


Elastic is the most important part of swimwear because it ensures the swimsuit stretches, fits snugly against the body, and stays in place when in the water. Swimsuit fabric will stretch over time, but the elastic will make sure the garment keeps its shape. Elastic keeps the garment flat against the body, and prevents seams from rolling over and exposing the lining.

There are a couple different types of elastic for swimwear, and we will go over what kind of elastic to use for swimsuits.

Rubber Elastic

Rubber elastic is the best kind of elastic for swimwear and the most popular choice. It's waterproof, resistant to chlorine and saltwater, UV resistant, and can withstand exposure to sunscreen and sun tan oils. It provides a snug and comfortable fit while remaining durable and long-lasting.

Rubber elastic can be used for the construction of swimsuit straps, around the edges of bikini tops and bottoms, and to add ruching for a slimming effect.

Clear Elastic

Clear elastic is a lightweight, ultra-thin, and invisible elastic option. It is not a good choice for swimsuits, and it's more suitable for bras, lingerie, and lace stabilizers. 

Clear elastic is not recommended for swimwear due to its limited durability in harsh swimsuit conditions. When exposed to chlorine and saltwater, it will break down, become brittle and lose tension over time. It will also discolor and yellow with extended sunlight and UV exposure.

Braided Elastic

Braided elastic can sometimes be an option for swimwear. Make sure to use choose options that are advertised for swimwear, not just normal braided elastic. Braided elastic for swimsuits is made with cotton and rubber to resist chlorine, saltwater, and sunscreen. It's distinguishable by its off-white color.

Foam Cups

Foam cups (also called swim cup inserts or molded cups) are small padding inserts that are sewn into the swimsuit. They provide shaping, support, and coverage and have a seamless appearance.

Swim cup inserts can create more flattering bust silhouettes, and push-up style ones can add volume to the chest. They also avoid visible nipple outlines, which is particularly important for light colored and thin swimwear.

The foam cups are typically made from lightweight, quick-drying, swimsuit-safe materials and come in various sizes to accommodate different cup sizes. Skin tone and black are the most common colors.


Underwires are an optional sewing notion that can be used to provide support to the bust area of a woman's swimsuit or bikini. Underwires are thin flexible wires that are coated in plastic or silicone to prevent rust and corrosion.

The benefits:

  • Provide support for women with larger busts.
  • Better appearance, contouring, and definition of the breasts.
  • Provide support during physical activities, movement and water sports.
  • No falling out or sagging appearance.

The negatives:

  • Uncomfortable when worn for extended periods.
  • Requires additional size information using bra size to get a comfortable fit.
  • Not necessary for all body types.

Swimsuit Hooks

Swimsuit hooks are one of the most common ways to secure straps and fasten bands. Hooks are often referred to as bra hooks and G hooks. When sewing swimwear, measure the width of your strap and purchase a hook that has an opening large enough for it.

Woman in swimsuit against ocean background

Metal Hooks

Metal swimsuit hooks are the best choice for swimwear hooks. They are heavier weight, durable, and easily maintain strap tension when without bending or breaking. With metal swimsuit bra hooks, there is minimal risk of a bikini top accidentally coming undone.

Metal bathing suit hooks can withstand frequent use, harsh water conditions like chlorine and saltwater, and the roughness of washing machines.

Plastic Hooks

Plastic swimsuit hooks are made from lightweight plastics, like nylon or polypropylene. They are more flexible and bendable than metal versions and are often cheaper. However, it's common to replace plastic hooks with metal ones when they break due to lower durability. 


O-rings are a type of swimwear notion that can be functional or decorative. These round rings can be used to connect different pieces of fabric, such as an o-ring bandeau bikini top, or be decorative with an iconic pattern like tortoiseshell.

Plastic O-rings

Plastic o-rings are a popular choice because they are lightweight, durable, and waterproof. They can be made from acrylic, cellulose acetate and resin.

The benefits:

  • Waterproof. Chlorine and saltwater-resistant.
  • Can be made in any color or pattern.
  • Usually seamless.
  • Smooth and won't snag fabric.
  • Inexpensive and affordable.

The negatives

  • Standard colors limited to black, white and clear.
  • Smaller and thinner o-rings can be more brittle.
Shop Plastic O-Rings >>

Metal O-rings

Metal o-rings are a common choice because they are readily available, durable, and come in versatile metal tones like silver and gold. Look for heavy-duty rings that are advertised as chlorine and saltwater-resistant, are thicker, and made from zinc alloy.

The benefits:

  • Durability.
  • Available in classic metals like silver and gold. Nylon coated o-rings offer more options for colors.

The negatives

  • Metals may corrode and rust when exposed to swimsuit conditions.
  • Often have a seam or an opening.
  • More expensive.
  • Harder to find larger sizes.

Budget Saving Tip: 

Consider buying o-rings in bulk or purchasing a multipack. This can help reduce the cost per o-ring and make them a more affordable option.

Clasps and Fasteners

A clasp or fastener is used to secure different parts of a bathing suit, such as the straps, back closure, or bikini sides. These closures are made with two pieces, with each part attaching to either end of the swimsuit strap, enabling them to link, slide, snap or click together securely.

There are different kinds of materials used to make swimsuit clasps, and we will review each of the options.

Metal Clasps

Metal clasps are a popular choice for swimwear because they are reliable and able to securely hold garment straps together under tension. The heavier weight, touch, and feel of metal clasps and buckles convey a heightened sense of craftsmanship and quality. Standard colors are silver and gold, while rose gold and black are sometimes available.

Plastic Clasps

Plastic clasps are commonly used in swimwear due to their low cost, lightweight, and versatility. Standard color options are clear, white, and black. There are many styles available, giving designers the freedom to choose the best option for their needs.

Shop Plastic Clasps and Fasteners >>

Stoppers (also called tips and cord ends)

Stoppers are small finishing details that are used to cover rope ends and knots at the end of garment strings like bikinis. They are also called tips, cord ends, rope end locks and even dangly bits. Stoppers are often used for swimsuit straps, lace-up sides or backs, string bikinis, halter ties and designer bathing suits.

Metal Stoppers

Metal stoppers for swimsuit straps and bikini strings are a luxurious final touch but also signify high-quality craftsmanship in swimwear design. These small but mighty hardware pieces conceal ugly knots, are durable in water environments, and greatly enhance the aesthetic of swimsuits by adding a glimmer of silver or gold.

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Wooden Stoppers

Wooden stoppers are a great option for those who want a more natural, earthy and organic touch in their swimwear designs. They are lightweight and come in many rich wood tones. Wood beads with large holes to fit the string and straps can also be used as an alternative finishing option.

Plastic Stoppers

Plastic stoppers are not commonly used in swimsuit design. Stoppers are an optional swimwear notion that adds crisp finishing details. But cheaper swimsuits typically opt not to use them, and instead, swimsuit straps and strings are finished off with a knot or sewn closed. However, plastic stoppers can add a clean finished look to swimwear strings at an affordable price point.

Pro Tip for Designers: 

Consider the price point for your swimwear when choosing cord ends. 

For luxury swimsuits, opt for metal stoppers and finishing details. Top-tier designers often have these metal notions custom-made with their logo. For easy casual swimsuits, it's more cost-effective to use affordable plastic stoppers or omit them entirely.

Sliders and Rings

Sliders are used with rings to connect straps to swimsuits and bikinis. Slides are often referred to as 8s, tri-glides and strap adjusters. They are used to adjust the fit and length of straps, allowing for a customized and comfortable fit.

Metal Sliders and Rings

Metal sliders and rings are one of the most common types used in swimwear. They are durable, sturdy, and can withstand the harsh conditions of saltwater and chlorine exposure. 

These components are available in different metallic finishes such as silver, gold, black, rose gold, and even rainbow titanium. Nylon-coated sliders and rings offer a wide range of colors, making it simple to match the fabric too. This gives designers the freedom to choose the perfect match for their swimsuit designs.

Budget Saving Tip: 

Consider purchasing sliders and rings in bulk or wholesale to save money. Many suppliers (like us!) offer discounts for large volume orders, which can help to reduce the overall cost of the swimwear project.

Plastic Sliders and Rings

Plastic sliders and rings are lightweight and affordable. They are a great choice for budget-conscious designers and bathing suits with a lower price point. They are available in a wide spectrum of colors, with black, white, and clear being standard options. 

However, cheap plastic sliders and rings can be prone to breakage, especially when exposed to high temperatures (like hot tubs) or prolonged UV exposure.

Shop Plastic Sliders and Rings >>

Choosing the right swimwear notions is important for making high-quality and comfortable swimsuits. By understanding all the different types of swimwear notions and how to best use them, you can create amazing swimwear for yourself and customers. 

Woman wearing a dark brown bikini holding a sunhat

What do you use when you make swimsuits?

Tell us in the comments below! 👇 


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