Safety 1st - Secure Lights 49 MHz Audio Monitor: 4 channels to minimize interference Sound lights Power and low-battery indicators Audio jack for listening with earphones Belt clip and carry loop Volume control 49 MHz frequency More than 600' range Secure Lights Baby Audio Monitor includes 2 energy-saving AC adapters draw energy only when units are on Baby safety monitors are better for the environment and your wallet Requires 3 AAA alkaline batteries (not included)