This part of ISO 228 specifies the verification, by means of limit gauges, of cylindrical threads, the dimensions and tolerances of which are given in ISO 228-1. For industrial applications (see for example ISO 1179), it may be necessary to carry out additional checks. Since this 55o profile has different elements to be verified, it is necessary to provide for several GO and several NOT GO gauges: a) the threaded GO gauges (see clauses 6 and 7) shall ensure that the profile of the machined piece does not exceed the maximum of material provided for by the tolerances applied to the dimensions of the profile defined by ISO 228-1; b) the threaded NOT GO gauges for the threads of the pieces (see clauses 6 and 7) fix the minimum material limit on the flanks of the thread. NOTE - Reference checks may be carried out in specialized laboratories.