These surgical stainless steel instruments in three sizes to match the osteotomy drills: 3.5mm, 4.0mm, and 4.5mm. They are used to accurately cut a soft tissue circle down and through the periosteum that is easily removed with a small spoon excavator and hemostat or mouse tooth tweezers. The inscribed rings at the top of the trephine cylinder correspond to the different diameters i.e., one ring = 3.5mm, two rings=4.0mm, and three rings=4.5mm. The hole(s) on the side facilitate cleaning and indicate speed of rotation as well as direction. Rotate clockwise. The extension "nipple" locates the pilot hole opening and allows for a slow side to side and front to back "wobble" cut technique to completely sever the periosteum because the bone is seldom perfectly flat.