, but "38" is not a standard pitch designation (these are typically even numbers like 8/16, 16/32, etc.). Document Page 38
Second, the standard defines four tolerance classes (Classes 4 through 7) to control the fit between internal and external splines [20†L41-L44]. These range from loose-running fits to tight fits, allowing engineers to precisely specify the intended function. ansi b 92.1 pdf 38