Av-jefe Avl670-sh4 Earhook Tan Color Mini Headset Mic for Shure Wireless Microphone Compatible with Shure Body-Pack Transmitter Models: T1, ULX1, UR1, PG1, PGX1, PGXD1, SLX1, BLX1, BLXD1. (Not Compatible with Mipro, Peavey, Beyer wireless microphone system) Polar Pattern : Omnidirectional Frequency : 50 Hz - 18,000 Hz Sensitivity : - 60 dB +/- 3dB Impedance : 1,500 Ohms +/- 30% (at 1 Khz)