Q. What transmitter will the 555 work with?
A. The 555 is available in three different configurations. The 28272 (negative shift) is for Futaba and Hitec transmitters when using Futaba 'J' servos. The 28572 (negative shift) is for Hitec and Futaba transmitters when using Hitec 'S' servos. The 28672 (positive shift) is for Airtronics and JR transmitters when using Airt 'Z' and JR style servos.