Big Boys on light sprung toys "MXZ Sport Models" need heavy springs. These are 13-5/8" from long tip to end of the big coil. Most XP models are delivered with springs for 150 pound riders and that doesn't cut it for most of us USA cheeseburger eaters. These are the "Tug Hill Special" mogul smoothing suspension saving rear torsions you need. Check out our HPG adjustable/rebuildable rear shock package also to really smooth the ride. These fit XP, XS 2008-2018 NON-R Motion skids 120" & some 137"(measure your oem spring for the 13-5/8" long tip to outside of coil), and come as a pair.