3500mAh High Capacity: Higher capacity than original battery, longer-lasting performance. Easy to Use: Simply quick install with included screwdriver and plastic tool. Considerate Details: Foam strip for cushion absorbing, durable and longer than originals battery wire for better connection, sponge tape well protects the connector wire from damage. Safe Performance: Built-in protection circuit well protects the rechargeable battery from over-charge, over-discharge, short-circuit. Compatibility: Compatible with Harman Kardon Onyx Studio, Onyx Studio 2, Onyx Studio 3, Onyx Studio 4.