“MAX 33T” rear derailleur: 33T Max eTap AXS rear derailleurs work with 12-speed cassettes from 10-26T up to 10-33T maximum and are marked “Max 33T” on the back of the derailleur. These work as either in 2x or 1x configurations. In a 2x set up, they will work with standard AXS front derailleurs paired with standard spindle cranksets, or wide version front derailleurs paired with wide spindle cranksets (both marked “WIDE” on the front derailleur and on the spindle of the crankset).
“MAX 36T”: wider gearing rear derailleurs work with 12-speed cassettes from 10-28T up to 10-36T maximum and are marked “Max 36T” on the back of the derailleur. These work as either in 2x or 1x configurations. In a 2x set up, they will work with standard AXS front derailleurs paired with standard spindle cranksets OR wide version front derailleurs paired with wide spindle cranksets (both marked “WIDE” on the front derailleur and on the spindle of the crankset).
XPLR / “MAX 44T”: The XPLR eTap AXS rear derailleurs work with either 10-36T or 10-44T cassettes. This derailleur is 1x compatible only. XPLR rear derailleurs will be marked with both “XPLR” and “Max 44T” on the rear derailleur near the b-bolt. They are compatible with both standard spindle and wide spindle version 1x 12-speed cranksets.