Frequency: 433.92MHZ
Sound: 75DB
Transmitter:8X5.2X0.56CM
WT:21g (battery included)
Battery:Lithium CR2016×2
Receiver: 4.5X2.8X1.1CM
WT:13.5g(battery included)
Battery:CR2032X1

Put the card in the wallet, on the desk or stick it on the fridge. and the receiver with keys, when you can't find the keys, just push a button on the card, and the receiver will sound alarm within 1 second.
The alarm will last for 5 seconds then stopped.
Working distance: 25-40meters.