This is a Sanwa compatible receiver. It works with FHSS-4 and FHSS-3 protocols.Features:1. FH3/FH4 compatible.2. High performance CPU enhances precision feel.3. 4 channel support4. Micro size (25.5x22x17.3)5. Antenna-less6. Fail-safe function7. Operating Voltage: 3.5-8.4v8. Weight: 5g9. Battery Volt..