Replacement battery fits 31 Myphone compatible models. Specifications: 900mAh, 3.7V, Li-ion. Compatible with: VEX IQ controller, 3350, Saiet BASIC, Halo 3, Holo A, ZiO Dual D1 and 25 more compatible models. Replaces: MyPhone BS-41, MyPhone BS-45, MyPhone MP-U-2, Leagoo BT-C2, VEX VEX-228-2779, Mini Keyboard SL-1102A and 5 more. Myphone replacement battery designed for Mobile/SmartPhone devices.