Here's the most useful app for drag racers at the Napierville Dragway race track. Get all your time slips directly on your phone. No more small piece of paper! You can even look at the history of your time slips (up to 50 races history per racer). Each history time slips include the Density Altitude at the moment of that single race! The Density Altitude is needed for serious bracket drag racers to properly calculate their dialin time for each race. The Density Altitude is updated every 5 min