Suitable Models: Universal Material: Stainless Steel Package Size: 7.5*2.5*2.5cm 3/4" to 1" Billet Shaft Adapter Pulley Bore Reducer Sleeve Bushing Sheave Key SL This steel shaft sleeve adapts a crankshaft from 3/4 to 1 diameter. It comes with step key that offsets from 3/16 to 1/4. Applications: Alters motors with a different diameter shaft Alters pulleys for a different speed or belt Reduces the necessity of buying a new motor or pulley to maintain existing components and speed/power requirements. Adapts larger wheel bores to smaller axels Works with Gas Engine Crank Shafts to enlarge the crank diameter to fit pulleys, gear boxes etc. Parts specification: Sleeve inside diameter 3/4 Sleeve outside diameter 1 Sleeve length is about 3 Sleeve Keyway slot 1/4 Step Key Length is about 2 The sleeve and step key are designed to exact fit on your 3/4 diameter crankshaft with 3/16 keyway and enlarge it to 1 diameter with 1/4 keyway. * Professional Installation Highly Recommended No instructions included * All items are d New unless stated otherwise on the listing. We sell DIY (Do It Yourself) Items with a few exceptions. We take no responsibility in teaching you how to install. Professional installation is strongly recommended.