Shimano Part no.:Y0GY98010. 1 x Shimano Lock Ring with Spacer for CS-M8100/CS-M7100//M6100. Deore CS-M6100. Shimano SLX CS-M7100 12 speed cassette • Aluminum Lock Ring & Spacer. For use with their 10-45T & 10-51T cassettes; these cassettes require the Shimano TL-LR15 Lock Ring Removal Tool.