For use with all SSTE's. Also for use with TTE's having serial #3480 or higher. Fulltone Tape echo's use a relay-activated footswitchable Echo Cancel… Unlike vintage Echoplexes Fulltone Tape Echoes don't route the playback head signal through the echo cancel footswitch which absolutely kills the delay sound if you use a cable over 6 feet in length. With the Fulltone ECF you can use any standard guitar cable up to 500ft if need-be. And there’s no need to power the ECF to see its bright Red & Green LED’s as the power is taken from the TTE or SSTE through the cable connected to it... Pretty slick eh?