WLPBDX - Minature Keychain Panic Button transmitter
datasheetprice each: $70  
Specifications
Dimensions 2.25" L x 1.25" W x 0.48" H (57x32x12mm), excluding keyring eyelet
Power two CR1616, CR1620, or DL1620 3V lithium cells (supplied)
Current Consumption 5 mA average while transmitting
Battery Life three years (typical)
Measured Range 300 feet minimum in open air, four quadrants
Accessories snap-action key ring
Number of Channels one channel
Operating Frequency 315Mhz