This is a Sanwa/Airtronics M17 RX-491 2.4GHz 4-Channel FHSS5 SSL Telemetry Receiver.
Plug in Bind
2.4 GHz FHSS5 Spread Spectrum System 4ch
Compatible with Telemetry (RPM and Temperature measuring only with the SUPER VORTEX Series)
Compatible with SSL (SUPER VORTEX Series)
Ultra Response Mode (SUR)
The smallest and most light receiver in the class
Note: This receiver is only compatible with the M17 Radio System.
Frequency: 2.4GHz FHSS5
Nominal Input Voltage: 3.7-7.4V"
Compatible Radio: M17