D Ring inside sizes: Approx:20mm, Thickness: 2mm conversion : 1 inch = 25.4mm or 1mm = 0.0393 inch Quality metal d shape rings: non welded d rings help to stabilize the bit laterally, it is sturdy and durable because of the nickel plated material and suitable thickness Easy to apply: use a metal d ring to make adjustable straps, ties and belts, will not be out of shape or collapse easily under load, and is easy to clip stuff in and out Multi usage: these metal d rings can be applied to handbags belts, belt buckle, backpacks, collars, luggage straps, camera bag accessories, etc.