Editing Rotary combination lock (section)

===Wheel sandwich construction===
Wheels are typically made of a three-layer sandwich. The outer layers, known as the ''wheel case'', contain the gate and surround the externally-toothed ''wheel center'', ''change key cam'', and ''lever arm''s. When a change key is inserted into the lock mechanism, it forces apart the lever arms, which then permits the wheel center to rotate freely. This in turn allows the owner to set a custom combination.<ref name=MSLG06/>{{rp|3–4;6}}