If you are setting up Stage Bottles, Need to add D-Rings to your Primary Back or Side mount Systems then the Dive Rite D-Ring Kit is what you are looking for. Kit consists of a 2" (5.1 cm) D-Ring with a 1/4" Diameter, an Adjustable Ring Clamp and a D-Ring Holder. All components are manufactured from Corrosion Resistant 304-Grade Stainless Steel for Durability and Long Life. The Ring Clamp is Easily Adjusted with a Flat-Bladed Screwdriver and can be adjusted to accommodate 7.25" to 8.0" (18.4 to 20.3 cm) Cylinder Diameters. Kit is covered by a 12 month limited warranty.