ANLEON S2R Receiver Wireless In-ear 526-535Mhz

Receiver operating time: up to 12 hours, 2 x 1.5V AA (not included)
Operating Range: 80m(environment dependent)
RF Output Power: <10mW
Signal-to-noise ratio(1mv,peak deviation) typ.70 db(A)
Frequency Response: 20Hz~18KHz

Powered by 2pcs Alkaline batteries or (NiMH) rechargeable batteries , Lithium AA batteries not recommended for S2