The concept of
calibration entered the gripper world when IronMind compared the variation among grippers to that in uncalibrated
barbell plates to explain why there may be slight variations from one gripper to another. Most barbell plates are uncalibrated, which means that they rarely weigh precisely the same as their face value, but a calibrated barbell plate must meet established criteria. In the gripper world, Strossen writes, some people mistakenly call a gripper calibrated when it has merely been rated for its level of difficulty. Ironically, while IronMind introduced the idea of gripper calibration and discussed its limitations, Captains of Crush Grippers—especially the No. 3 Gripper—became the de facto standard by which other grippers were measured. In 2004, IronMind made some adjustments to its benchmark No. 3 Gripper to ensure that it conformed to its historical standards, In 2012 Cannon PowerWorks introduced the RGC (Redneck Gripper Calibration) method where it determines the actual poundage required to close each gripper, tested out near the end of the handle. The following chart, lists both originally published IronMind poundage's from the center of the handle, and the Cannon PowerWorks RGC poundage's from the end of the handle. (* These grippers are designed to help bridge the gap between the benchmark-level grippers, and are rated halfway between the No. 1, No. 2, No. 3, and No. 4 CoC Grippers, respectively; thus, these are their interpolated poundage ratings.) In bold text are the three original grippers.
Certification Men No. 3: In 1991, IronMind created a certification program to recognize people who closed the Captains of Crush No. 3 Gripper under official conditions. This certification has become the universal benchmark of world-class grip strength.
Richard Sorin was the first person certified when he closed the No. 3 in 1991. John Brookfield was the second person IronMind certified when he closed the No. 3 in 1992. Since then, more than 288 people around the world have been officially certified as closing the No. 3.
No. 3.5: In 2008, IronMind expanded its certification program to include the No. 3.5 Gripper. Tex Henderson became the first person to officially close the No. 3.5 when he accomplished the feat on August 5, 2008. 21 additional people have since officially closed the No. 3.5 Captains of Crush Gripper.
No. 4: IronMind released the Captains of Crush No. 4 Gripper in 1994, but no one was officially able to close it until
Joe Kinney was certified in 1998. Only five others have officially closed the No. 4 since then: Nathan Holle (2003), David Morton (2003), Tommy Heslep (2004),
Magnus Samuelsson (2004) before IronMind introduced the "credit card rule" (to fit the short side (54mm) of a credit card between the handles of the gripper before it is closed) and
Carl Myerscough (2023) after the introduction of the credit card rule. A
YouTube clip of Samuelsson closing the No. 4 Captains of Crush Gripper has been viewed over two million times.
Women No. 2: In 2011, IronMind opened its certification program to recognize women who successfully closed the Captains of Crush No. 2 Gripper. Since then, four women have been certified. The first was Adriane Blewitt in 2011. In 2013, Amy Wattles and Elizabeth Horne were certified. In 2022, Lyudmila Gaiduchenko joined the list. In 2013, IronMind expanded the certification program to No. 2.5 Gripper for women, but none have performed this feat to date.
Credit card rule In 2008 IronMind was criticized for changing the rules on how it certifies people who have closed its Captains of Crush No. 3, No. 3.5 and No. 4 Gripper. The company decided the official starting position for any attempt must be demonstrated by fitting the short side of a credit card between the handles of the gripper before it is closed. However, some competitors protested against the new requirement claiming their hands were too small to achieve the new requirement (a small hand making a grip will create a smaller gap between the handles than a larger hand). In response IronMind explained the requirements for certification were changed because some competitors had begun using questionable techniques to close their grippers. It maintains if anyone cannot close a Captains of Crush No. 3, No. 3.5 or No. 4 Gripper with its required starting position, but can close a weaker Captains of Crush Gripper, the reason is a lack of strength not a problem with hand size. == Jesse Marunde and philanthropy ==