On base model machines, plain handwheels are used. They are laser engraved with 50 marks (inch) or 100 marks (metric) and numbers for reference. Adjustable zero handwheels allow you to stop at any given point, loosen a knurled wheel in the center of the handwheel and rotate the laser engraved collar back to the zero mark before starting the next cut without moving the position of the handwheel. This means each time you are starting from zero rather than from a random number, making your depth and cut calculations easier. This eventually means less mistakes. 4400- and 4500-series lathes and 5400- and 2000-series mills include these upgraded handwheels as standard equipment.