Sena Headset Earmuff Cradle 20S/20S EVO/30K/50SConvert a helmet headset to an over the head headset by attaching the main module of a 20S, 20S EVO, 30K or 50S to the earmuff cradle Detachable microphone Uses the same durable headband and earmuff bracket as the Cast Uses the same microphone arrow design as the Cast Uses HD speakers for audio Noise Reduction Rating: Over the Head: 28 dB Sound Level Conversion Rating: Over the Head: 33 dB Signal to Noise Ratio: Over the Head: 34 dB