SENTRY 4 BUTTON TRANSMITTER 403/433MHZ DUAL LEARNINGSENTRY 4 BUTTON TRANSMITTER 403 433MHZ DUAL LEARNING The SENTRY DUAL FREQUENCY LEARNING remote control is a handheld transmitter that has the capability of learning a button from an existing remote in both the 403 and 433MHz bands. It is capable of learning binary, inverted binary, trinary, inverted trinary, French, Smart, and Code Hopping transmitters into each of the four buttons. RR TX4SND