The SRAM Rival AXS Power Meter Crank Arm is compatible with SRAM Rival AXS DUB cranksets. This is the image on the left below. Please note, this power meter will NOT fit the older generation Rival GXP or BB30 cranksets (image on the right), as these cranksets use a different spindle size and interface.

SRAM Rival E1 AXS 2x Direct Mount Chainrings
SRAM DUB PressFit Road 86.5 MM Bottom Bracket