Ski Skett Shark Trainer Skating Roller Ski Bundle with NNN Bindings, Fully Assembled Simulates cross-country skate skiing Lightweight 24-inch aluminum shaft (21-inch shaft available as option) Narrow, high-profile, medium-speed rubber wheels (Fast and slow wheels available as an option) Performs best for experienced skate skiers training on smooth pavement and mostly flat terrain Please send us a product customization request including your height, weight, shoe size, binding type (NNN, SNS Profil or SNS Pilot), shaft length and wheel speed.