You are able to connect up to 4 of these gigantic heat mats together to provide nearly limitless heated surface area! Our basic commercial mat is huge. At 60-in. by 21-in. it’s big enough for six flats! Plus each add-on mat is the same size and big enough for six more! Basic unit includes 6-ft. 120-volt AC cord. Add-on units plug into each other using an included connector. Full instructions printed o mat. UL-listed.