Features: Compatibility: Convert a multi speed hub to single speed wheel. for all for or Sram 7 to 11 speed cassette type hub body, mountain and road. NOTE: It will NOT covert the hub into fixie, so the hub is still a freewheel hub.<br> High quality stainless steel: The flywheel is made of high-resistant stainless steel, the strength and hardness are twice that of ordinary 316 stainless steel, and the hardness reaches 18 degrees.<br> Chain Size: The sprocket is for the chain width from 1/2" x 3/32" to 1/2" x 11/128". ( 7 speed to 11 speed chains). You can use your original chain! With a choice of different sprocket teeth selections, you can for always get the perfect pedaling ratio.<br> Specifications: Material: Stainless steel<br> Color: silver<br> Teeth: 12T/13T/14T/15T/16T(optional)<br> Processing technology: CNC cutting<br> Packing size: approx. 12x8x2cm/4.72x3.15x0.79in<br> Applicable: Mountain bike multi-speed to single-speed, suitable for 7/8/9/10/11-speed chain<br> Package Includes: 1 x Single-Speed Bike Freewheel<br> note: No retail package.<br> Please allow 0-1cm error due to manual measurement. pls make sure you do not mind before you bid.<br> Due to the difference between different monitors, the picture may not reflect the actual color of the item. Thank you!