Life Fitness Anchor Resistance Tubes attach to pullup bars and uprights to create an anchor point to pull, push, and twist away from. The outer gray nylon sleeve covers the inner resistance tube from nicks, cuts, and overstretching. Move your starting point away from the anchor point to increase resistance profile. These tubes are offered in two different styles. Dual Grip Handles: Push / pull against the anchor point Loops: Attach around waist, quad, ankle and move away from anchor point Warranty: 90 Days