Floors are rarely as flat as the drawings, and stair treads are never level with the rail above them. The 533/424 absorbs that with an adjustable collar: the base bolts flat to whatever the surface is, and the collar pivots to bring a 1.67-inch OD post plumb, or to hold a rail tube at the pitch of a stair. Lock the collar and the angle stays put, without shimming or grinding a fixed flange to fit. It is machined in 316-grade satin stainless steel, the marine grade for pool decks, waterfront walkways, and cruise work, which is also where the 42.4 mm European rail size is most often specified. The satin finish hides fingerprints and keeps glare off an exposed post base. Use it with the 1.67-inch tubing and the matching 316 fittings in the same family. Ships from US inventory.