The Wein PSR-500-2W is the 2-channel Receiver in the Pro-Sync series that features a "H" household plug. An unlimited number of Pro-Sync receivers can be triggered by a Pro-Sync transmitter set to the same channel. Plugged into your remote flash, the Pro-Sync receiver is in a "standby" mode. Pro-Sync receivers can easily pick up the signal from behind backdrops, soft boxes, even around a roomful of wedding guests. Nothing else can trigger the receiver, not even a full-power flash fired inches away. They work indoors or out, with a maximum range of 600' (indoors).The receiver draws power from the flash to which it is connected; there are no batteries to change on the receiver. This receiver has household type 2-prong plug. For additional versatility, each receiver also has a standard PC terminal.