A cylinder is the portion of a lock that the key fits into. Cylinders can be removed and changed out and the internal parts, known as tumblers can be changed by a locksmith, and the cylinder can be reinstalled with a different key than before or several cylinders can be keyed alike. Cylinders have a low profile. There are a variety of cylinders which include key in the knob locks, rim cylinders and round mortise cylinders.
New Replacement 1" Mortise Cylinders, Rim Cylinders, Thumbturns, and Dummy Mortise Cylinders