WORKING DISTANCEUp to 50MFUNCTION?Wireless ON/OFF and Volume UP/DOWN ?There are 2 radio frequencies can be chosen. They are 315MHz and 433MHz respectively.FEATURES?W-2 is the advanced version of W-1 wireless radio transmitter. ?Compare to W-1, the biggest difference is W-2 comes with 4 buttons, which makes it more versatile. COMPATIBLE WITHAF-4R, M-7X RGBA, M-9, M-11, MB-20, S-500, Z-390, Z-1520