These are 3D printed adapters that should be considered as single use items. They typically get damaged while removing the pinion gear when replacing motors.
Single piece, you need one adapter per motor
What is included with Hardware:
QTY 1: 3D printed adapter
QTY 2: M4 nuts - insert into the backside
QTY 2: M4 X 35mm (Extends through 7R gear box)
QTY 2: M5 X 12mm (Extends through adapter into 887 Motor)