3 or 4" To 1" Billet Shaft Adapter Pulley Bore Reducer Sleeve Bushing Sheave Key p20241126676 Suitable Models: Universal Material: Stainless Steel Package Size: 7.5x2.5x2.5cm 3 or 4" to 1" Billet Shaft Adapter Pulley Bore Reducer Sleeve Bushing Sheave Key SL This steel shaft sleeve adapts a crankshaft from 3 or 4 to 1 diameter. It comes with step key that offsets from 3 or 16 to 1 or 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 or 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 or 4 Sleeve outside diameter 1 Sleeve length is about 3 Sleeve Keyway slot 1 or 4 Step Key Length is about 2 The sleeve and step key are designed to exact fit on your 3 or 4 diameter crankshaft with 3 or 16 keyway and enlarge it to 1 diameter with 1 or 4 keyway. x Professional Installation Highly Recommended No instructions included x 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.