EZ-Xtend Boat Zipper - Adds an Extra Inch to Shrinking Boat Canvas - No Sewing Required (Black, #8 - 94) Shrinking boat canvas? End your snapping and zipping struggles instantly. Patented EZ-Xtend Boat Zipper is easy to use on all types of boat covers, bimini tops, and boat enclosures! Add an instant inch to relax the fit and cut to length right on the boat! Determine size of marine zipper needed before ordering. See sizing instructions below. Existing marine zippers must be in good condition. Compatible with YKK and Lenzip, but not RiRi Zippers. Cannot be used on marine zippers that are sewn shut on one end.