The Di2 Battery Holder securely mounts your Di2 battery inside of your ShockStop Seatpost.

This kit is for mounting your Di2 battery inside your ShockStop Endurance Seatpost or ShockStop PRO Endurance Seatpost securely.

If you have the ShockStop 'PRO Race', you do NOT need this kit because any Di2 seatpost adapter will work in the 'PRO Race' version. If you have the standard ShockStop 'Endurance' or 'PRO Endurance' post then this kit will work but it is only compatible with the 27.2 mm diameter x 350 mm size.