Sanwa RX-391W 2.4Ghz FH-E 3-Channel Receiver. The RX-391W is a waterproof receiver, and is compatible with the Sanwa MX-6 radio system. Features: 2.4GHz FH-E 3 ch (SPREAD SPECTRUM COMMUNICATION SYSTEM) Waterproof NOTE: RX-391W is not compatible with telemetry function. Specifications: Frequency: 2.4GHz FH-E Channels: 3 Nominal Input Voltage: 4.8?6.0? Dimensions: 31.9x26.5x14.5mm Weight: 12.7 g Compatible radio: MX-6