Economy Kit: Spring kit only, no clutch weights are included. Works with any tire size.For general trail riding. Improves belt grip and backshift.Vendor Item # AW433700This item fits the following applications:Kawasaki KFX700 03-06Mudder Kit: Designed for mud riding with aggressive lug tires. Helps restore power loss due to addition of mud tires. Better low end power and torque to get tires turning in the mud.Quicker backshift which results in crisp throttle response. Reduced belt slip and clutch heat. This item fits the following applications:Polaris 700 Sportsman 05-06Polaris 700 Sportsman EFI 04-06