charlest...
at the moment, the spare ball is the gap in the RotoGrip lineup. It used to be aptly filled by the clear grenade, but that ball has been discontinued. While not a staffer, RG is all that I throw, hence I am on that eagerly awaits the new introduction into that area of the lineup (my clear grenade is showing some signs of cracking, and I cannot use plugged equipment...NIB replacements are next to impossible to find in the 14-15 weights).