I rated sena until it started not doing what it was meant to, battery might as well have been cheese for the time it lasted.Sena works well and you can get some very discrete units as they have some designed to work with specific helmets. I've an Arai RX 7V and you wouldn't know there's Bluetooth fitted and my girlfriend has an HJC is-17 where you replace the bottom cheek parts for Sena ones which have the electronics and buttons fitted in already.