Use this D-Ring hardware kit to install on helmets using all Simpson Safety Solutions SFI Head and Neck Restraint Devices. Models include the Hybrid Pro, Hybrid Pro Rage, and R3. An extra set of D-Ring hardware enables you to use your head and neck restraint system with multiple helmets. D-Ring Helmet Hardware Kit includes: 2 D-rings 2 screws 2 backing plates Only compatible with helmets that are pre-drilled for HNR (Head and Neck Restraint) devices.