A seatpost retention plug that holds an electronic shifting system battery securely inside ENVE carbon seatposts. Electronic shifting is the gold standard and more bikes are coming equipped with these groups. Housing the battery into the seatpost is an elegant solution and a good use of space. Available in 25.4, 27.2, and 30.9/31.6mm sizes, these plugs are designed to provide excellent battery retention and interface perfectly with ENVE carbon seatposts.