“MAX 33T” 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 near the B-Bolt. They work both in 2x or 1x configurations, with both standard and Wide cranksets.
“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 near the B-Bolt. They work both in 2x or 1x configurations, with both standard and Wide cranksets.
XPLR, or “MAX 44T”: the XPLR eTap AXS and XPLR AXS rear derailleurs work with 10-36T, 10-44T or 11-44T cassettes. XPLR eTap AXS rear derailleurs will be marked with both “XPLR” near the B-bolt. They are compatible with 1x cranksets only, both standard spindle and Wide versions. Please note that the mechanical Apex XPLR rear derailleur is not compatible with 11-36T cassettes.