This spider mount sits between the Gen 4 CX Bosch drive unit and the outer 4 bolt chainring. Compatible with the Bosch Gen 4 Performance line CX. This is the offset 'Boost' version. If you need the 'Non-Boost' version you can click Bosch Non Boost Spider.
Allows the motor to take a standard 104 BCD chainring. Chainring bolts not included.
Solid, quality no nonsense part. Has enabled me to have a greater choice of chainring rather than just using the stock E13 / buying expensive rings. Very useful and speedily dispatched by Ebike shop