Therefore, on snowbikes, there’s one more thing to think about: although the Thermo-Bob limits use of the radiators in the extreme cold of snow bike riding, the snow that gets on the cylinder and engine cases still acts as a "third radiator", sucking heat out of the engine. A PST engine jacket helps keeps snow off the engine and keeps engine temps up especially for cold powder riding days. It is made from a light weight nearly indestructible material and can be taken off in minutes or worn all winter season. The cover also folds down in stages so you can adjust venting for riding on packed snow or warm days. Each cover has been custom made to fit the specific bike model. With the combination of a ventable engine jacket, Thermo-Bob, and a water temp gauge you can keep engine temps in the goal range.