You can use something like a two-prong lamp extension cable, I have one similar to these: http://www.aliexpress.com/item/USA-Canada-2-Prong-Male-to-Female-Powe

You can use something like a two-prong lamp extension cable, I have one similar to these: http://www.aliexpress.com/item/USA-Canada-2-Prong-Male-to-Female-Power-Extension-Cord-Nema-1-15P-1-15R-Power/32362907226.html http://www.aliexpress.com/item/USA-Canada-2-Prong-Male-to-Fe... Or just cut and splice the regular power cord, that's what I did with a room fan. The Sonoff has thick plastic covers for the terminals with little teeth to hold the wires in place as it's meant to be put directly in line with a power cable. Note that the relay inside is claimed rated for 10A, so I wouldn't power appliances with it. It also only switches the hot and neutral lines, so if you need a 3-pin connection you have to splice it to the line and neutral while keeping the ground line connected. It goes without saying however that you should be extremely careful and only splice wires like this if you know what you're doing. Don't damage cable insulation while stripping, wire things up to the right connectors, don't leave exposed wires, use the correct wire gauges for your load, etc. Mains electricity is dangerous, yo.