Mortise lock with 100% stainless steel mechanism. This model can be installed on steel or aluminum gates and fits perfectly into our custom welding box. The massive stainless steel hook and adjustable latch bolt makes this a one of a kind lock. The combination of the hook (dead bolt) with the SHKM or SHKW keep provides a secure anchoring of your gate while preventing the gate from being pried open as the dead bolt's "hook" locks into the keep's anchoring plate. The latch gap required is keep dependent, but the SHKM Hybrid keep requires a 7/8" latch gap.