breakdown. In the spirit of sportsmanship, such a win will often not include the loser's car and often calls for a rematch on a later episode, believing that they will not take the car unless it was a clear win on the track, and not by default. Notes A common occurrence is "set matches", such as import vs. domestic, new vs. old models of a certain make, or races of popular former cars, such as current technical advisor Charles Hendrickson's "Woolly Mammoth", an altered 1976 Chevrolet Vega wagon that beat several more sporty cars. Other matches have featured motorcycles, trucks, and even snowmobiles. Recent shows have been sponsored (with prizes going to the winner such as free Bridgestone tires or several cases of Shell Q Motor Oil), with Series Four featuring NAPA Auto Parts as the series presenting sponsor for both the regular and All Out series, owing to the show's growing popularity. Current sponsors are NAPA and Valvoline. The arm-drop start prevents bracket racers from using the delay box, a popular device that is typically used in this genre of drag racing. Typically, with the Christmas tree, the delay box is designed to allow a driver to press the throttle pedal on the second amber, allowing the box to launch the car one second, or in the case on the third amber, a half-second later. The arm drop's unpredictability prevents this popular technique from being used, which forces drivers to watch the official to launch the car. In 2008, the American Drag Racing League was forced to a Pinks-style arm drop start for the final two rounds of their 1/8 mile races when lightning damaged the Christmas tree at US 131 Motorsports Park in Martin, Michigan. On the May 28, 2006 episode of WindTunnel with Dave Despain, the show's producer and host Rich Christensen claimed that some losing racers tried to buy back the vehicle after the race, which Rich tried to eliminate in later seasons. However, one race resulted in a win by default when the engine block overheated, leading to a win by "catastrophic failure". In the spirit of sportsmanship, the winner gave the car back to the loser, noting that a win by default caused by such severe mechanical failure is improper, and promised a future rematch. On multiple episodes Rich has allowed a car that has lost due to mechanical failure to be granted back