graduated 1/4″ to 1-1/4″, shaft 6-1/4″ (16.0 cm) Michele Trephines is an instrument crafted for use in removing circular bits of bone to increase access to specific areas. This type of instrumentation is ideally used in neurosurgical procedures such as craniotomies. This trephine features a long slim shaft that at one end features a T-shaped handle which allows for a rotating motion and at the other end a circular blade. This trephine is available gradated ¼” to 1 ¼” with a 6 ¼” shaft and is available in 5.0 mm od, 5.5 mm od and 8.0 mm od making it suitable for a vast array of surgical scenarios.