Roto Grip Cosmos Polyester

Every bag needs a plastic ball, and the Cosmos is a good looking one. Polyester cover, three piece symmetric core, polished to 3500 grit.

The numbers are exactly what you want from a spare ball: a very high 2.68 RG and an almost non-existent .006 differential. Translated, that means it barely flares and barely hooks. Throw it straight at your corner pins and it will hold its line regardless of how much oil is on the lane or how badly the pattern has broken down. That predictability is the whole point. It also makes a reasonable first ball for a new bowler who is still working on a consistent release, and it doubles as a straight-line option on very dry lanes.