Right from the PBA web site this is the equipment you can use and it addresses plugged equipment.
Q: What equipment can I use?
A: The PBA follows most USBC guidelines regarding bowling ball specifications, with a few exceptions. Plugged balls can be used in PBA Regional Tour, PBA Senior Tour, and PBA Tour Qualifying Rounds competition. Only balls with clear plugs that adhere to the guidelines below can be used in PBA Tour competition.
As for finger and thumb inserts, the following guidelines apply:
• In PBA Tour competition, clear plugs and solid inserts (slugs) may be used in finger and thumbholes, provided they do not exceed three fourths (3/4) of an inch across the diameter of the hole. When manufactured inserts are used in conjunction with clear plugs or solid inserts, the total thickness cannot exceed three fourths (3/4) of an inch.
• In PBA Senior Tour, Regional Tour, PBA Tour Qualifying Round, U.S. Open, and PBA World Championship competition, there will be no specific plug limitations for plugged equipment. However, no foreign matter may be placed in the plug area, and all equipment shall otherwise comply with PBA regulations.
• In all phases of PBA competition other material may be used solely for gripping purposes provided it can be readily removed for spot checks.
• In all phases of PBA competition materials used for gripping purposes cannot exceed one quarter (1/4) of an inch across the diameter of the hole.
• In all phases of PBA competition manufactured inserts cannot exceed three fourths (3/4) of an inch across the diameter of the hole.
Go here to find a complete listing of approved equipment.
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