The 025 Series Piano Hinge, made of 0.025" thick Steel, is a light duty hinge that's ideal for small boxes or doors that require a small but durable hinge. These are plain steel, with no holes, and have a factory "mill" finish.
Available in open widths of 3/4" or 1" open, these have a 0.062" diameter pin and 1/4" knuckles. Very small!
No plating or other coatings, though they do have a light oil residue to prevent them from rusting during shipping.