Footswitches like the BOSS FS-5U are rugged, heavy duty switches for controlling various functions on devices in the BOSS/Roland range, and are also compatible with a number of third-party products.
What the folks have BOSS have to say about the FS-5U:
Roland/BOSS offers two types of sturdy metal footswitches for different applications. The FS-5U (silver) is a momentary "unlatch"-type footswitch, and the FS-5L (black) is a latch-type footswitch with an LED to indicate status. Both footswitches can be connected using ordinary guitar cables. Please consult your owner's manual for compatibility.