Description: 【Compatibility】: The Bicycle Single Speed Freewheel is suitable for 10/11 speeds drum conversions. 【Package Contain】: The package includes a 1×9mm spacer, a 1×4mm spacer, a 1×1.8mm spacer, a single speed cassette freewheel, end rings and lock rings for convenient usage. 【Premium Material】: This bicycle single speed cassette cog made of alloy, It boasts high strength, sturdiness, and durability for long term use. 【Design】: Specifically designed for the conversion of fixed gears of 6 bolt disc drum singlespeeds. 【Feature】: Its lightweight design won't add extra burden to your bike while its scientific design increases contact area to protect the drum body. Specification: Material: Alloy Size Chart:Inner Diameter 2.4cm/0.94inch Outer Diameter 6.83cm/2.69inch Package Includes: 1pc 1×9mm Spacer, 1pc 1×4mm Spacer, 1pc 1×1.8mm Spacer, 1 Single Speed Cassette Freewheel, 1 End Rings, 1 Lock Rings Note: Please allow slightly errors 1-2cm differences due to manual measurement.