Turbo 2 N 1 Grips Bowling Accessories. The same great versatility as the Quad but now available in 78 outside diameter. Perfect for women and youth bowlers. The Quad 4 N 1 insert combines 4 great styles, Power Oval, Perfect Oval, Round Mesh and Perfect Oval Mesh, into just one product. As an added plus, each Quad insert is designed with a patented Glue Groove to minimize excessive adhesive from seeping to the surface of the ball during installation. Durometer Hardness 40 Shore A.