This device is a combination of an amp buffer and amp switchiing delay. For those that may be using an amplifer with T/R relays that have a slower time constant than the transceiver. This switching delay can cause hot switching. Some amplifiers that need this device is Kenwood TL-922, Collins 30L-1 and Heathkit SB-200. Some of the Ameritron amps also have slow switiching relays. This happens when you transmit before the T/R relay in the amplifier closes. Some have reported failure of the transceiver power output transisitors. Also it can cause failure of the amplifier band switch. The amp delay/buffer will solve this issue. It has a varialble time constant control that is adjustable between 125ms to 2000ms. Also the unit will work with all radio's and amplifiers. It has both negative and postive inputs from the transceiver. The unit is powered by 12-15 V DC from an external dc source.. The enclousure is 4x2 /1/2x 1 1/2 inches.