As far as we are aware these are the first cryogenically treated hook knives available worldwide.
Cryo offers only benefits with no drawbacks. It does not make the tools any harder (more brittle) or more difficult to sharpen as raising the RC hardness does. The initial heat treatment quenching process changes the crystalline structure of the steel from austenite to martensite. the perfect steel is 100% martensite after heat treat, which has a very fine grain structure, but that is virtually impossible to achieve. There is always some retained austenite and the larger crystals caused by this at a microscopic level reduce the edge retention of a fine edge tool.
What cryo does is convert nearly all of the retained austenite to martensite giving that holy grail of steel, a very homogenous fine grain structure that is hard and tough but not brittle. In very simple terms the process makes the tool edge last significantly longer without making it any harder to sharpen.