Aaahhh ok so one receptacle per heater.. cool thx broThe first product on that page is a prewired ranco with 1 receptacle up to 1800 watts. Being prewired means it can be plugged into an existing outlet. If you were to buy a unit off of amazon you would have to wire it yourself, mine is wired to 4 outlets. This picture should help you a bit.
http://www.etcsupply.com/images/etc_prewired/ranco_etc_wired.jpg?osCsid=6j5j9k5gftogs34a547isvp617
All the green wiring is non existant on a normal new unit. I had mine wired by an electrician friend. You can use a splitter (not sure if correct term) to run multiple heaters.