Take all the guesswork out of finding the perfect distance for your throwline with the Viper Pro Line Marker Tape. This convenient tool allows you to mark precisely where your throwline should be in relation to the front of your board. Engineered measurements ensure that your throw line is the correct regulation distance, ready for tournament play! The Pro Line tape is easy to use and requires no tools, simply attach the end of the tape to your board with a dart, find the distance you need and mark it! The tape then folds back into its case for easy storage to any event!