These are New Old Stock (NOS) MAY 2015 designed to work with the Radiometrix TXM-418-3V transmitter module listed in a separate listing. 

RX2  - 418-14-5V
DOUBLE CONVERSION FM SUPERHET
· SAW FRONT END FILTER, IMAGE
REJECTION 50DB
· SUPPLY 3.0 TO 6.0 VOLTS @ 13MA
· 40KBIT/S, -F VERSION , -100 DBM
SENSITIVITY @ 1PPM BER
· 14KBIT/S. -A VERSION , -107 DBM
SENSITIVITY @ 1PPM BER
· LO LEAKAGE, < -60 DBM
operating voltage 5V