I can never quite decide if I think it's an advantage that HeatTrak sells all of the components for its heated walkway and stair mats separately, so you can add on to a configuration without needing another power unit, or whether it's a ripoff that you can't use the mats to begin with without making an additional purchase. I have an old house with limited outdoor electrical outlets, so the 6-foot cord is never long enough, either. Be that as it may, the HeatTrak system itself is fantastic! I've used the stair mats for several years on a set of front-door concrete steps that used to give me homeowner liability nightmares in the winter, and this year I added a walkway mat to the ever-icy backdoor entry (thus the need for a second power unit). Just this morning I enjoyed that safe (and a little smug) feeling again as I woke to the results of night-long freezing rain, sleet, and slush to find my steps and walkway ice- and snow-free. Next year I'm definitely adding a doormat to the garage entry! (As well as, sigh, another separate power unit).