Fahrer Akku E-Bike battery covers are constructed using high-quality neoprene which offers insulation to help extend battery life in colder weather, and protect ebike batteries from scratches and impacts. Features: Battery covers help maintain working internal temperature 4.5mm thick neoprene offers insulation and slight impact resistance for E-bike batteries Specifically designed for Shimano STEPS system frame mount batteries Note: Only recommended for temperatures under 59degF (15degC)