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2.3.3 A delivery must be made entirely by manual means.

2.3.5 A player may use special equipment to aid in grasping and delivering the ball if it is in place of a hand or major portion thereof lost by amputation or otherwise.

https://www.worldbowling.org/wp-content/uploads/2014/06/World-Bowling-Statutes-and-Playing-Rules-2016-01-01.pdf