How to Choose the Right Zipper 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 of the options and variations of zippers can be overwhelming. We answer a lot of questions about the different types, sizes and styles of zippers, so to help shed some light on the subject, we`re going to compare and contrast the options so you know exactly how to select the perfect zipper for your next project. 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 width of the zipper teeth in millimeters when the zipper is closed. So a #5 zipper`s teeth measure around 5 mm across, a #10`s teeth measure around 10 mm and so on. This makes selecting a size easy, because the bigger the size, the larger the zipper teeth will be. Sailrite stocks zippers in sizes #4.5 for home décor projects like cushions and pillows, #5 for medium-sized projects like larger cushions and bags, and #10 zippers for large projects like sail packs, boat enclosures and tents. Coil vs. Vislon One way to narrow down your zipper selection is by the type of tooth on the zipper. There are two main types: coil and Vislon. Vislon is the most common marine zipper, and it features teeth made from Delrin plastic that are molded onto the zipper tape. This construction makes them strong and practically weatherproof. Vislon zippers come in sizes #5 and #10. Coil zippers feature plastic teeth that, as the name implies, look coiled. The teeth are sewn on to the side tape with polyester thread. Coil zipper teeth are stronger and more flexible than Vislon zippers, making coil a great choice for curved applications like a smile window on an enclosure. However, because the teeth are sewn on, they don`t last as long in the sun as Vislon zippers do. Coil zippers are available in #4.5, #5, and #10 sizes. Continuous vs. Finished Continuous and finished are terms that refer to the length and style of the zipper as a whole. Finished zippers are sometimes also called `jacket zippers` because they are most commonly used on coats and jackets. Finished zippers feature a starter box and pin at one end of the zipper tape and stops at the other end. These zippers also come with sliders included. Finished zippers are used for applications where you want the sides of the zipper to separate completely like on a coat, a genoa sleeve, or the side panels of a cockpit enclosure. A continuous zipper is a little different. These zippers do not have a beginning or an end point (no starter box or zipper stops). Continuous zippers are usually sewn into a project at both ends like on a bag, tent or cushion. These zippers do not come with sliders, so you will have to purchase one separately and add it to the zipper chain. If one or both ends of your continuous zipper isn`t sewn shut, you can add zipper stops to the chain to keep the slider from falling off the end of the chain. Locking vs. Non-Locking The terms `locking` and `non-locking` refer to the zipper sliders. Locking zipper sliders have a small lock mechanism in them that keeps the slider in place unless the slider`s tab is pulled. This prevents the slider from moving on its own if the tape is forced apart or if the center of the slider is pushed. Non-locking sliders, on the other hand, allow the zipper to separate by pulling on any part of the zipper slider or even by pulling the zipper teeth apart. This is useful for an application where you would want to be able to quickly separate the zipper, like on a genoa sleeve. Locking and non-locking zippers are available for both coil and Vislon zipper teeth. When selecting a slider, be sure you choose a slider that is compatible for your zipper chain in both size and type. For example, a #5 Vislon zipper will need a #5 Vislon Slider, and so on. Then you can select the slider material (plastic or metal) and locking or non-locking.