Rail systems specified to the European 42.4 mm standard need mounting hardware in the same size, and the 510/424 is that flange. It takes 1.67-inch OD tubing in its collar, locks it with a set screw, and fastens through a pre-drilled base. Cruise, coastal, and imported-specification projects use it to close a run against a wall without adapting a 1.5-inch part. It comes only in 316-grade stainless steel, polished or satin. That is deliberate: 42.4 mm rail is most often specified where salt air, pool chemicals, and weather are part of the brief, and 316 resists the chloride pitting that shortens the life of 304 in those settings. Pair it with the 1.67-inch tubing, facia mounts, and welded floor flanges in the same 316 family. When the round base will not clear a corner, the Cut Wall Flange 511/424 offers the trimmed profile. Ships from US inventory.