Work Great!
Quote below from,

http://www.hardracing.com/Tire%20War...hickenHawk.htm

"PRO-LINE Tire warmers - This is the Mac-Daddy of all warmers! The Pro-Line model is Temperature Adjustable with a Digital Display that shows the actual tire temperature while the warmer runs. Temperature set point is changed with the push of a button- Range up to 212 degrees F. All the other features of our warmers plus the most accurate and easiest temperature control of all."