This mortise lock is constructed of steel components with rounded faceplate ends. It features an adjustable, spring-loaded hook latch projection and an adaptor faceplate which allows for use on wood and vinyl patio doors. This lock works with mortise style, surface-mounted patio door handle sets with 45 degree angled keyway positions when in the locked position. The mounting hole centers of this lock measure 3-11/16 in. and 4-5/8 in. from center to center, and the rear housing corners are square. This mortise lock is used by many patio door manufacturers. Selection Tip: To ensure the perfect match is selected prior to purchasing, the lock will need to be removed to compare the following 4 features (besides the width of housing): 1) The distance of the mounting holes measured from center to center, 2) The faceplate ends; rounded or square, 3) The position of the slotted keyway when in the locked position; at 45 degree angle or vertical, and 4) The shape of the housing corners at the rear; square or slanted. Installation Tip: Watch the manufacturer’s How-To Video that is linked to this item page..