each unit includes: P-Cover Cap P-Cover "A" Compatible with XT RD-M8100-SGS Rear Derailleur. "B" Compatible with XTR RD-M9100-SGS Rear Derailleur but differ in materials, appearance, finish, size, etc The "A" which indicates that the parts are the same in materials, appearance, finish & size etc. The "B" which indicates that the Parts are usable, but differ in materials, appearance, finish, size, etc. .
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