Per battery mount for SM BTR2 and SM BTDN110, seatpost mounting, 27.2–28.6 mm
The battery mount for the Shimano Di2 batteries BTDN110 and SM BTR2, for mounting in the seatpost
For 27.2 to 28.6 mm seat posts
Herstellerinformation: PRO, High Tech Campus 92, 5656 AG Eindhoven, Netherlands, https://pro-bikegear.com