Bought this relay to control a 1500w heater wired to a G4 remote switch (controlled via text messages. Very cool). The relays in this remote switch were 10 amps and I was afraid that if I ran 1500 watts at 110 volts through them the relays would trip so I bought this 30 amp relay to activate the heating circuit. Works great. As others have pointed out, the transparent housing makes it easy to identify the normally-on and normally-off switching contacts (1 each), as well as the input and output contacts. There are no instructions included but to be honest if you're buying this device you should already have a reasonable working knowledge of the circuits so the lack of instructions isn't really a problem. I'll buy more if needed.