API Certificated Drill tools saver sub Top drive protection connector tool joint
Cross subs/top drive subs/protective subs/lift subs are primarily used in drilling operations to connect the upper and lower drill strings in different connectors. They can also be used to protect other tools in the drill pipe (called saver subs) or to deliver vented air to the drill bit face above the drill bit (called the drill bit sub).
Cross subs are typically measured shoulder to shoulder. Typical lengths range from 6" to 28" long, in 2-inch increments of AISI 4145H, AISI 4145H Mod, AISI 4340, AISI 4140, 4142, and non-magnetic materials. All connections are phosphate coated or copper-plated for improved corrosion resistance. Cross subs are available in three basic types: B-type (male) * C-type (female)
; B-type (male) * C-type (male); C-type (female) * C-type (female).

