The Dark Bronze Mortise With Aluminum Thumbturn Cylinder is a component used to activate a lock without the need for a key. This 5-pin cylinder is constructed from diecast zinc and features an aluminum thumbturn. It measures 1" in length and has a 1-5/32" diameter. The cylinder is designed with an AR MS-type cam for compatibility with standard mortise lock setups. The assembly includes a 3/16" cylinder ring to assist with installation. This cylinder is finished in dark bronze, providing a consistent appearance for architectural door hardware applications. The ring thickness is 13/66". This mortise cylinder is intended for use in glass entrance systems, including door rails, side rails, and various U-channel or spider fitting configurations. The 5-pin design allows for manual operation of the locking mechanism from the interior side of the door. The included 3/16" cylinder ring is used to adjust the projection of the cylinder from the door surface, ensuring a proper fit with the door rail or stile. The dark bronze finish is applied to the exterior components to match existing hardware in commercial or architectural settings. This product is a standard replacement or installation component for mortise-style locks requiring thumbturn access.