Bought these at the end of last season and used them twice. $350.

Woodcraft Dual Temp Gen III Tire Warmers with soft carry case. Like New. 0.-_prt3198-jpgWoodcraft Dual Temp Gen III Tire Warmers with soft carry case. Like New. 0.-dsc_5503_new-warmer-features-progressii-jpg

Here are the specs from http://www.woodcraft-cfm.com/cgi-bin/commerce.cgi?preadd=action&key=30-2100:

Key Features:
Even Heat Distribution - The small gap heating element leaves smaller spaces between the coils, ensuring the whole tire is heated evenly, virtually eliminating cold spots.
Great Insulation - Our special insulation is extremely efficient allowing us to keep the warmer construction thin while still providing great performance. You will love how easy the low profile design makes installation and removal of the warmers.
Side Curtains - Our fleece side curtains eliminate the #1 cause of heat loss by protecting the tires from side winds. In many cases we have seen up to a 15 degree increase in rim temperature compared to warmers without them.
Easy to install / remove - A large one piece velcro strap secures the warmer to the tire without hooks or cords getting in the way.
Durable - We used only the best components and subjected all internal connections to rigorous tension tests to be sure these warmers are built to last.
LED Indicator Light - Pick your tire temp with the flick of a switch the display 'on' light is red and turns to green when the tire is at temperature.
Voltage: All Woodcraft tire warmers are designed to run off a 120V power source. Generator users will need 1000 watts minimum to run a set.