I had a pair with that same control which makes me think they're made by the same company. they worked fine except the one time I forgot to turn it off or unplug them. came back to find it burned a hole through the inside.
so not so confident in their build/materials quality. after all they're not supposed to be able to burn through.
I had an inexpensive set of tire warmers that looked a lot like those. I had to go back and look at an old track photo to recall what they were, but they weren't the same. Mine were Tyrsox or something like that. I think I paid around $130 or $150 for them, used.