Leverage means the weightblock is placed at a 45º angle at release. This translates to a pin to PAP distance of 3 3/8".
Label is a reference to the center of your grip. Its a holdover term from when all bowling balls had pancake weightblocks. For the average bowler, the label is around 5" from the PAP. However, it could be more or less depending on how high (or low) you track.
All in all, it an agressive drilling best suited for bowlers with a lot of natural control in their sytle or wide open lane conditions.
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Good luck & good bowling