In bowling, how come some bowling balls have a small piece drilled off of it?

I’m not talking about the finger holes. In some balls I see at the Bowling alley, there’s a small part of it that’s drilled off, near the finger holes. What is it for?

because the balls are all weighted, and still all the same size. the manufacturer drills a hole into the ball and removes a calculated amount of weight, then fills in the gap with a less dense and therefore lighter material.

Related posts:

  1. What type of grip should I get drilled?
  2. How often do bowling balls crack when drilled?
  3. The Bowling Ball As Your Best Friend
  4. Maddak Bowling Ramp,Aluminum Bowling Ramp – Two Piece,Each
  5. How do you go about buying a bowling ball?