It is API spec 7-1 type D sub used for lifting the entire BHA assembly. This sub is manufactred inn 4145H material and has hardness requirement on the down OD. All the requirements of standard specification are taken care of in manufacturing of this product. A lift sub is a type of downhole tool used in the oil and gas industry to facilitate the lifting and handling of the drill string during drilling operations. It is a short, threaded pipe fitting that is designed to provide a point of attachment for a lifting device, such as a hoist or crane.

The lift sub is typically placed near the top of the drill string, just below the rotary table. Its primary function is to provide a safe and efficient way to lift and handle the drill string during drilling operations. The lift sub is typically designed to withstand the high stresses and pressures of drilling operations, and is made from high-strength materials, such as alloy steel.

Lift subs come in various sizes and configurations, depending on the specific requirements of the drilling operation. They may be equipped with additional features, such as a swivel joint to allow for rotation of the drill string during lifting, or a safety mechanism to prevent accidental detachment of the lifting device.

Overall, the lift sub is an essential component in the drilling process, as it enables the safe and efficient lifting and handling of the drill string, reducing the risk of accidents and equipment failures during drilling operations.