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: 4.8-6.0v
• Dimensions: 31.9x26.5x14.5mm 
• Weight: 12.7 g 
• Compatible radio: MX-6