DP Lock – The locking mechanism is to be attached onto one of our pole mounts. The lock is used to keep the lower jaw on a typodont open while on a pole mount. When the knob inserts into the 35mm side that is the opening you will see. When the knob is inserted to the opposite side then you will have a 22mm limited opening. The adjustable opening allows you to teach and learn how to work with various patients.