Setting up a stage bottle rig for decompression/safety stops requires a variety special hardware. You need to install D-Rings for clipping off the cylinders to decompression/safety stop lines that will hold them securely. The Highland by XS Scuba Stainless D-Ring Holder (Taco) is an intricate component of this hardware. The D-Ring Holder (Taco) can be placed under a metal hose clamp with room to install a 2" (5cm) D-ring. The D-Ring Holder measures (L x W) 1.5" x 0.65" (3.8cm x 1.67cm). The Highland by XS Scuba 316-Stainless D-Ring Holder (Taco) makes a great save-a-dive-kit item.Highland by XS Scuba Stainless D-Ring Holder (Taco):Required Hardware for Setting-Up Stage Bottle RigsWorks in Conjunction w/2" (5cm) D-RingsCreates Clip-Off Point for Stage Bottles On Deco/Safety Stop LinesDurable Corrosion Resistant 316-Stainless-SteelGreat Save-A-Dive-Kit ItemDimensions: (L x W) 1.5" x 0.65" (3.8cm x 1.67cm)Holds Rig SecurelyPlaced Under Metal Hose Clamp Around Cylinder