API 7K Rotary Table Master Bushing and Insert Bowl for Oilfield Product Description Master bushings can be divided into three kinds of structure, hinged, solid or split. There are two kind of diving way, pin and Square. It is adapted to rotary table by size from 17 1/2 to 37 1/2(49 1/2 in) respectively. When insert bowl is assembled,(some haven't insert Bowl), it can be connected with rotary slips and roller kelly bushing that are manufactured accordance with API Spec 7k.