HOW TO CHOOSE SIZE (See Video) Start by checking the back of your broken zipper slider; most zippers have a size number (1-10) embossed on the back of the slider. Once you know your zipper size, our sizing chart below will determine which is right for you. If your zipper doesn?t have a number on the back, you can simply measure the width of the zipper teeth in millimetres or inches. SIZE GUIDE: -Small Zipper Slider: Teeth and Coil Sizes 1-4 -Medium Zipper Slider: Teeth and Coil Sizes 5-7 -Large Zipper Slider: Teeth and Coil Sizes 8-10. Don't know your zipper size number? Measure Teeth / Coil Width: 1 to 4. 5 mm or 0. 04 to 0. 18 in = Small, 5 to 7. 5 mm or 0. 19 to 0. 30 in = Medium, 8 to 10 mm or 0. 31 to 0. 40 in = Large The is a replacement zipper slider that repairs zippers without tools or sewing. It has a patented spring plate design that enables it to fit over a range of sizes. Teeth or coil, metal or plastic, fixing zippers on jackets, bags, tents, clothing, car covers, wet suits, shoes, sleeping bags, jeep windows, etc. It supports sustainability in that it encourages reuse of products and is, itself, reusable. All parts are designed and manufactured in the USA. Easy to install, it can fix most items with zippers in minutes. HOW TO CHOOSE SIZE: (See Video) Start by checking the back of your broken zipper slider; most zippers have a size number (1-10) embossed on the back of the slider. Once you know your zipper size, our sizing chart below will determine which WinZip is right for you. If your zipper doesn?t have a number on the back, you can simply measure the width of the zipper teeth in millimetres or inches. SIZE GUIDE: Small Zipper Slider: Teeth and Coil Sizes 1-4, Medium Zipper Slider: Teeth and Coil Sizes 5-7, Large Zipper Slider: Teeth and Coil Sizes 8-10. Don't know your zipper size number? Measure Teeth / Coil Width: 1 to 4. 5 mm or 0. 04 to 0. 18 in = Small, 5 to 7. 5 mm or 0. 19 to 0. 30 in = Medium, 8 to 10 mm or 0. 31 to 0. 40 in = Large LARGE WORKS ON Zipper Sizes 8-10, Examples wetsuits, boat covers, canvas tents, heavy duty clothing, jeep windows NO TOOLS OR SEWING REQUIRED: WinZip isn?t your average zipper repair kit. It?s a replacement zipper slider that you can install without tools or sewing. REPAIR MOST ZIPPERS EASILY: Apparel, Backpacks, Tents, Boats, Marine, Sleeping Bags, Purses, Jackets, Pants, Bags, Luggage, Wetsuits, and More. Works on Open-End, Closed-End, and Invisible / Watertight Zippers. PROBLEMS GETTING YOUR NEW ZIPPER STARTED? See the video "How To Get Your Zipper Started on Closed End Zippers"