Give it all youve got. The BLX14/SM31 Wireless System can handle your most intense workouts. The SM31 Fitness Headset is made from corrosion proof materials. You can sweat on it. Shout into it. And it will perform just as you need it. Built to ensure rock solid signal from transmitter to receiver. Shure BLX Wireless Systems eliminate interference and drop-outs. Youll sound completely clear. And thanks to one-touch Quickscan technology all the hard work is done for you. Locating the best frequency for your performance is as easy as pushing a button. No trial and error. No complicated set up. Just one press.