Model E4 from Click N Dig is a newer and improved version of our original two receiver model, RFK-1004. This Key, Wallet, Remote Finder is a convenient and high quality gadget that works! It beeps the right device every time. Simply press and hold down the color coded button on the radio transmitter until the corresponding colored receiver beeps to find the item up to 60 feet away and hidden under the pillows or across the walls. Radio frequency penetrates walls, cushions, leather etc. So the receivers beep from the other side of the walls, or when hidden deep in the couch or sofa pillows. Now never lose your keys, wallet, remote control, cell phone etc. Other technical details: Frequency: 433 MHz Sound Volume: 90-105 dB, Remote distance range: 60-80 feet. Shop with confidence! All orders are shipped within 24 hours.