This specification covers Grade C-75 casing and tubing and C-95 casing in the sizes and wall thicknesses shown in the standard lists (Tables 1.1 and 1.2), and the dimensional tables (Tables 6.1 through 6.6). It also includes requirements for couplings and thread protectors. Dimensional requirements on threads and thread gages, stipulations on gaging practice, gage specifications and certification, as well as instruments and methods for inspection of threads are given in API Std 5B and are applicable to products covered by this specification. Although this specification, in conjunction with API Std 5B, permits manufacturers authorized to use the API monogram on round-thread casing to manufacture and apply the monogram to buttress and extreme-line casing. considerable skill and know-how is required for the tooling for, and machining of, these joints. Therefore, any manufacturer who desires to produce these joints is advised to consult with manufacturers who have produced these joints before attempting their manufacture.