We always need to attach more stuff to our equipment to free up our hands when we need them. Lanyards for lights, cameras, gauges, game bags, or maybe even a fish stringer when spear fishing. D-Rings can be threaded to the straps of out BCD's allowing us to attach clips. Having some spares D-Rings in your gear bag is a must for the serious diver.
Threading a D-Ring under the webbing of your weight belt when threading the belt to your lead gives a great attachment point for clipping of accessory and helps prevent weight slippage along the belt. Keeping items clipped to your equipment make you more streamline in the water and prevent items such as gauges from damaging the environment. 2" (5.1 cm) Stainless Steel construction gives corrosion resistant and long lasting usage. D-Ring is great Save-A-Dive Kit item. Buy several so you're never caught short handed on a dive.