Threaded stem casters are the most common of all stem casters. These casters are mounted the same way a screw is drilled in. Threaded stem casters have a stem that screws into a threaded hole, bracket, insert, or socket on a piece of equipment. The stem must be matched up with the hole size and thread count of the hole, bracket, or socket. This measurement is critical for the caster to be mounted. If the stem size and thread count do not match up with the mounting hole, the caster will not work.