NOTE: Photo shows merely a standard Model 5000 mill with standard handwheels. The 5500/5510 model looks identical except for the addition of adjustable "zero" handwheels on each axis. The 5000/5100 mill can be ordered with adjustable "zero" handwheels replacing the standard handwheels that would normally come with that model. Adjustable handwheels allow the machinist to option of resetting the handwheel to zero (or any desired value) at any time. A locking screw is loosened, allowing the read collar to be rotated without moving the handwheel. The collar can be reset to a zero reading and the locking screw retightned to re-engage the collar so it moves with the handwheel. Being able to zero the handwheel at any time makes it easier to calulate your feed distance or stopping point for the next feed, thereby eliminating math errors.