Amazon.com: Sennheiser Consumer Audio Compatible with Sennheiser XSW 12-A XS Wireless Lavalier System - SK 20, ME2 and EM 10 Receiver - "A" 548-572 MHz : Musical Instruments
Sennheiser XSW 52-A Wireless Headmic Set A | Guitar Center
Sennheiser XSW 52 Headmic Set - B Range: 614-636 MHz | Sweetwater
Sennheiser XSW 1-835 Handheld Wireless System (A Band - 548-572 MHz)