construction cpsRF® GEN Response System User Manual Model BENZENE Base and KGEN2EI Keypad Frequency 2.4 GHz The construction cps RF Model KGEN2EI keypad is a wireless portable device that along with a base unit Model, BIOGEN, makes it possible for a number of people to participate interactively in either a small or large group situation. The product accomplishes this by sending keypad switch closure information from the keypad to the base unit employing a wireless transceiver to receive the keypad signal.