"Bought this to replace a 100mm plain bolt fitted to outward opening timber door which had been forced. Bolt had ripped through timber as it was too close to edge so bought this necked bolt thinking it would be a stronger hole with the surface plate supplied. Disappointed at the quality, the back plate is quite thin and bends easily. Not suitable for fixing vertically upwards, any slight movement in the door and the bolt drops as its a sloppy slide action. My fault poor selection but needed something quick. Replaced it with one of the spring-loaded bolts, 85965 different as chalk and cheese. To be fair this should work OK horizontally but should not be relied on for security purposes."