This Listing is for one (1) Collins 30S-1 Amplifier 20.5 Foot Input Cable, made with High Quality Belden Cable & RCA Connectors This is a high quality, custom made Cable, which Collins designed to use with the 30S-1 Amplifier. the use of this cable will assure the IMD products across all bands will be up to Collins Quality Standards. It is basically part of the tuned input network and really should be used in keeping with good Amateur Radio Practices. There has been a lot of discussion if this length is really needed. The amplifier will work with any length of input cable, but the Collins Engineers felt it was necessary to keep the IMD products withing specifications at that time, and the use of this length of cable was recommended.