When access control is not needed, we recommend the use of Securitron's patented MXD door movement exit delay system. The MXDs handsome stainless steel housing is made to conceal proximity detection switches in addition to any regular Magnalock (available separately). This system is activated when the door is moved about 1" permitteed by MXDs original spring-loaded sex bolt but the door still remains locked. The MXD installation process needs no alteration or replacement of fire rated or non-fire rated latching hardware which already exists. But the best yet, false setting off is entirely eliminated by the ample 1" door movement permitted. And the entirely sealed design of this mechanism ensures that the MXD almost completely tamper resistant!