Multiplex RX-4/9 FLEXX M-LINK ID receiver, part number 55837. A compact 2.4GHz M-LINK receiver giving 4 proportional channels, expandable to as many as 9 switching channels when used with MULTIswitch FLEXX modules — any number of which can be daisy-chained onto the receiver over its bus, making it a strong choice for scale and functional models with lots of auxiliary switching. Adjustable ID, Smart UD technology and a hold/fail-safe function. Tiny and light at 34 x 19.5 x 11mm and 7g, operating from 3.5–9V, so it suits small helicopters and multirotors as well as fixed wing. Developed and built in Germany. Binds to any M-LINK transmitter including the SMART SX. CONDITION: used, supplied loose without original packaging. Please see photographs.