Viking Mirage® Quick Response Concealed Pendent Sprinkler VK464 is a thermosensitive glass-bulb spray sprinkler designed for installation on concealed pipe systems where the appearance of a smooth ceiling is desired. The sprinkler is pre-assembled with a threaded adapter for installation with a low-profile cover assembly that provides up to ½” (13 mm) of vertical adjustment. The two-piece design allows installation and testing of the sprinkler prior to installation of the cover plate. The The “push-on” and “thread-on” designs of the concealed cover plate assemblies allow easy easy installation of the cover plate after the system has been tested and the ceiling finish has been applied. The cover assembly can be removed and reinstalled, allowing temporary removal of ceiling panels without taking the sprinkler system out of service or removing the sprinkler