Straight subs: Used to connect drill stem members that have a similar OD.

Reduced-section sub: Used to connect drill stem members that have different diameters that warrant the cross-sectional change necessary to accommodate different connections.

Saver sub: Used to extend the life of the rotary kelly by taking the connection wear each time it is made up to a drill stem component.

Bit sub: Size availability ranges from 3 1/8” to 11” OD and 36” to 48” length.

Lift sub: A lift sub enables the safe, efficient handling of straight OD tubular—such as drill collars, shock tools, jars, directional equipment, and other tools—by using the drill pipe elevators.

Top drive sub: Top drive subs serve as the sacrificial element between the drill string and the top drive, reducing repair and maintenance costs.