Captains of Crush Grippers: designed and built for performance. 
The gold standard for building and testing hand strength, Captains of Crush Grippers are the single most important grip strength tool you can choose--for the fastest route to the strongest grip.
No. 2.5:  Bridge the gap between the CoC No. 2 and the CoC No. 3--at the upper end, it could be crucial for progress.
 No. 1252.5 (1 lb.)  No. 2.5 @237.5 lb. $29.95