Each of these HeatTrak HR-P Control units can control up to fifteen HeatTrak HR10-30 Residential Snow & Ice Heated Safety Tread, 10-Inch by 30-Inch, 120 Volt or five HeatTrak HR20-60 Residential Snow & Ice Heated Walkway Mat, 20-Inch by 5-Foot, 120 Volt (or a combination of each), so we needed two units to control two Step Mats coupled to four Walkway Mats and one for five additional Walkway Mats. These work pretty much as expected, with the following observations:
+ Easy To Install; connects to mats via a waterproof coupler
+ Heats Up Fast; was over 80 degrees Fahrenheit after fifteen minutes
See my individual reviews of the Walkway and Stair mats if interested those products.