Choosing the Right Zipper

Item # X-HT-300049

So many projects, from boat covers to pillows and everything in between, use zippers. When it comes time to select a zipper for those projects, however, all the options and variations can be overwhelming. This helpful blog will explain everything you need to know about zipper selection. Coil, molded tooth or metal, continuous or finished, locking or non-locking, single or double pull … don't worry, we explain it all!

Zipper Size

Let’s start off with zipper sizes. Zippers are sized with a number designation (e.g., #5, #10). These numbers are based on the approximate width of the closed zipper teeth in millimeters. So, a #5 zipper’s teeth measure approximately 5mm across, a #10 zipper’s teeth measure approximately 10mm across, and so on. (For exact measurements, look under the Specifications tab on each zipper's product page.) The bigger the number, the larger the zipper teeth will be and vice versa.

Determine a zipper’s size by measuring how wide the closed teeth are.

To easily find a zipper's size, just measure the width of the zipped teeth.

Sailrite® stocks zippers in the following sizes:

Size #4.5: Used for small home décor projects such as cushions, pillows and purses.

Size #5: Used for medium-sized projects such as cushions and upholstery, duffle/tote bags, backpacks and jackets.

Size #10: Used for large projects such as sail packs, boat covers, marine enclosures and tents.

Size #12: Used for large projects such as marine canvas, outdoor gear and portable shelters.

Size #15: Used for very large projects such as oversized sail packs and covers, large tents, and portable buildings and greenhouses.

Coil, Molded Tooth or Metal Chain?

One way to narrow down your zipper selection is by the type of tooth on the zipper. There are three main types: coil, molded tooth and metal.

You can get zippers with coil, metal or molded teeth. Which is which?

A close-up view of the three zipper chain types.

Let’s start with molded tooth. The molded tooth zippers we carry are made from DuPont Delrin® Acetal Resins molded onto zipper tape. (YKK® molded tooth zippers are called VISLON®; Lenzip® doesn't use a special term.) This construction makes them strong and practically weatherproof. Molded tooth zippers are the most common option for marine projects because they’re UV and corrosion resistant. We stock molded tooth zippers in sizes #5, #10, #12 and #15.

Coil zippers feature nylon teeth that, as the name implies, look coiled. The teeth are sewn onto the side tape with polyester thread. Coil zipper teeth are stronger and more flexible than molded tooth zippers, making them a great choice for indoor and outdoor projects with curves. Just note that polyester thread breaks down in the sun, so coil zippers should be kept covered to protect them from UV exposure in outdoor projects. We stock coil zippers in sizes #4.5, #5 and #10.

Metal zippers have polished metal teeth that secure together on the zipper chain. Because they can corrode, we recommend not using metal zippers for outdoor projects. They are ideal for bags and purses, backpacks, interior cushions and upholstery, and more. You'll find a selection of metal zippers on our website.

Continuous vs. Finished Zippers

What’s the difference between a continuous and a finished zipper?

Left: a continuous zipper. Right: a fully separating finished zipper.

"Continuous" and "finished" are terms that refer to the length and style of a zipper as a whole. Finished zippers are called this because they come with stops, sliders, and sometimes a starter box and pin preinstalled. You don’t have to add any parts to a zipper like this — it’s already finished. Within the category of finished zippers, there are separating and non-separating zippers.

Separating zippers are sometimes also called "jacket zippers" because they are most commonly used on coats and jackets. They feature a starter box and pin at one end of the zipper tape and stops at the other end. These zippers are used for applications where the sides of the zipper should separate completely, such as on a coat, a genoa sleeve or the side panels of a cockpit enclosure. You can even get water-repellent separating zippers!

On the other hand, the two halves of non-separating finished zippers don’t come completely apart. They have preinstalled sliders and stops, but no starter box or pin. Sailrite carries two varieties of non-separating finished zippers: bridge top and bag style. Both of these zipper types have permanent stops at both ends, but bridge top zippers have one slider while bag style zippers have two. Non-separating finished zippers are good for bags, jacket pockets and more.

All styles of finished zippers come in preset lengths, but you can cut them shorter if needed. Just make sure you add stops to the cut end or sew it into your application so you don’t lose your slider!

A continuous zipper is a little different. These zippers do not have a beginning or end point (no preinstalled starter box or zipper stops). You can order continuous chain in preset lengths and cut it to the length you need for your project. These zippers do not come with sliders, so you will have to purchase one separately and add it to the zipper chain. Continuous zippers are usually sewn into a project — like a bag, tent or cushion — at one or both ends. If you don’t sew one or both ends of your continuous zipper shut, you can add stops to the chain to keep the slider from falling off the end(s).

Locking vs. Non-Locking Sliders

Locking vs. non-locking zipper sliders.

How do locking and non-locking zipper sliders work? We'll tell you.

Now that we've covered zipper chain, let's turn to sliders — the piece that zips and unzips the chain. Locking zipper sliders have a small lock mechanism that keeps the slider in place unless the tab is pulled. This prevents the slider from moving on its own even if the zipper tape is forced apart or if the center of the slider is pushed. Locking sliders are great for trousers, jacket fronts or any other application where you need the slider to stay put until you unzip it.

Non-locking sliders, on the other hand, allow the zipper to separate by pushing or pulling on any part of the slider or even by pulling the zipper teeth apart. This is useful for applications where you need to be able to quickly separate the zipper, like a genoa sleeve or spinnaker sock.

We stock locking sliders for coil and molded tooth zippers, as well as non-locking sliders for coil, molded tooth and metal zippers. You can get metal or plastic zipper sliders, which both have their pros: Metal sliders are stronger, but plastic sliders resist corrosion.

Single- vs. Double-Pull Sliders

There’s one more decision you have to make when choosing a zipper slider: whether you need a single- or double-pull slider. The pull is the tab you use to move the slider and open or close the zipper. Sliders can have either one or two pulls.

Single- vs. double-pull zipper sliders.

Left: a single-pull slider. Right: a double-pull slider.

Single-pull sliders have a pull on just one side. The zipper can only be opened or closed from the side that has the pull on it. Think of most jackets, cushions, purses and other similar items. You’d only need to open and close these zippers from the outside, so there’s no need to have two pulls on the slider.

On the other hand, double-pull sliders do have two pulls — one on the front of the slider and one on the back. This allows the zipper to open from either side. Double-pull sliders are great for projects like tents and enclosures, which you would need to unzip from both the inside and the outside.

We stock single-pull sliders for all three zipper chain types and double-pull sliders for coil and molded tooth zippers.


When it comes to choosing the right zipper for your project, there are several important points to consider. Think about whether your application will be indoor or outdoor, whether the zipper will need to curve, whether your project will be in a marine environment, and more. Answering these questions will help you select either a molded tooth, coil or metal zipper chain. And taking some simple measurements of your project should help you determine if you can get a finished zipper in a preset length or if you’ll need to buy a length of continuous chain and cut the zipper to size yourself.

If you opt for a continuous chain, don’t forget that you’ll need to choose a matching slider. Be sure to get a slider that is compatible with your zipper chain in both size and type. For example, a #5 molded tooth zipper will need a #5 slider for molded tooth chain, and so on. Once you have the size down, you can select the slider material (plastic or metal), locking ability and number of pulls. You can also choose from our selection of top and bottom stops if your application calls for it.

When selecting parts for a continuous zipper, we recommend sticking to one brand. Pairing Lenzip sliders with Lenzip zipper chain and YKK sliders with YKK zipper chain will offer the best compatibility and performance.

Sailrite is your go-to resource for all things zippers! We stock a full and diverse inventory of zipper components: separating zippers, continuous zipper chain lengths, zipper pulls and sliders, and zipper top and bottom stops. We’re proud to stock both Lenzip and YKK brand zipper components. Both brands are giants in the industry, known for quality parts that last. Our Lenzip supply is by far our most robust zipper offering, with a wide variety of finished, separating and continuous zipper styles, colors and sizes, as well as sliders and pulls in a multitude of colors and styles to choose from. Think of Sailrite as your trusted zipper supplier.

Ready to shop for your zippers? Browse our large selection of Lenzip and YKK zippers now.

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Do you have any other questions about zippers? We're here to help! Share your questions and concerns in the comments section below or reach out to our dedicated customer service team.


This blog was updated in February 2023 to include updated product and inventory information.