Shimano's cylindrical Di2 batteries were designed to slide into seatposts, but "slide in" and "stay put" are different engineering problems. The MT-BINT-SP2 is a simple retention mount that clips around your BT-DN110, BT-DN300, or SM-BTR2 battery and keeps it secured inside the seatpost tube without rattling around or migrating downward when you hit rough roads. It also works with Campagnolo's EPS batteries for riders running that electronic shifting ecosystem.

The mount uses a clip-on design that wraps the battery body and holds it centered in the seatpost interior. A pull tab at the bottom gives you something to grab when extracting the battery—this matters because the alternative is tugging on the e-wire connector, which eventually damages the terminal and creates intermittent connection issues that are maddening to diagnose. When it's time to swap a dead battery or troubleshoot a shifting problem, you pull the tab and the whole assembly slides out cleanly without stressing the electrical connection.

Compatibility covers any standard 27.2mm round seatpost, which means you can use this mount across multiple bikes if you're swapping batteries between frames or running a spare battery for long events. It also fits Cervelo's SP18 D-shaped seatpost used on the R5 from 2017 onward and the Caledonia-5, despite the non-round exterior profile—the interior cavity accommodates the mount geometry. If you bought a frameset or replacement seatpost and need the battery retention hardware, or if your original mount cracked and the battery is rattling loose inside the post, this is the part that secures everything properly and makes battery removal a deliberate action rather than an accident waiting to happen.