1.1 .I This Standard covers requirements for squareand rectangular parallel keys and keyways intended forboth alignment of shafts and hubs, and transmittingtorque between shafts and hubs.1.1.2 Keys covered by this Standard have a relativelytight width tolerance. The deviations are less than thebasic size. Keys with greater width tolerance and withdeviations greater than the basic size are covered byASME B18.25.3M.1.1.3 The inclusion of dimensional data in thisStandard is not intended to imply that all sizes describedare production stock items. Consumers should consultwith suppliers concerning lists of stock items.