One knob to control it all Streaming audio through Bluetooth is a wonderful thing, but trying to use a touchscreen to find a song when you're on a boat and the water's choppy is not. This marine-rated Bluetooth control knob from Wet Sounds makes it a lot easier to pause, play, track forward, track backwards and adjust the volume on your iPhone or Android smartphone. Pairing is quick and intuitive, making Bluetooth control a lot easier than you'd think. The 3.5mm output makes it easy to connect the control knob to any marine receiver with an AUX input, or to the Wet Sounds WS 420 SQ 4-band equalizer. You can mount the water-resistant WW-BT-VC flush in your boat's dash or install it underneath, out of sight. It's also a great option for ATV riders or classic car owners who want to enjoy amplified music without replacing the factory radio.