Zipperstop Wholesale YKK&reg; 20" Boot Zipper YKK #5 Nylon Coil ~ Closed End ~ YKK Color 580 Black (1 Zippers/pack) Zipperstop Wholesale YKK 20" Boot Zipper YKK #8 Nylon Coil ~ Closed End YKK Color 580 Black (1 Zippers/pack) These zippers are thoroughly tested for strength and durability. The slider runs on two coils on each side; the "teeth" are the coils.