Gauge to indicate a correct alignment for the thumb hole of a bowling ball

摘要: A gauge for indicating the correct alignment a thumb hole of bowling ball having ring with circular abutment section central axis, an aperture through opening inside section, also track concentric and coaxial axis angular indicia on ring. fin is attached to extending in plane which includes axis. plate periphery fits rotates track, centrally located boundary generally flattened portion against top will bear opposite rounded bottom bear, index mark align indicate orientation be drilled ball.