The two silver parts on the back are reflective to ensure the safety of dogs walking at night. Material: Aluminum Bar SBR Foam Function: If a pet with blurred vision walks with an obstacle in front of it, the anti-collision ring will provide feedback when encountering an obstacle, helping to prevent accidental injury. Collar and bust size can be adjusted. Product Size: S = circle diameter 22CM (for 4-10KG), collar 28-40CM, bust 32-45CM M = circle diameter 33CM (suitable for 13-20KG), collar 32-45CM, bust 36-50CM Protect Your Pet: Designed for pets with vision impairments, helps pets with poor vision due to SARDS, glaucoma, cataracts, retinal diseases, trauma, and diabetes. Helps prevent collisions with walls or other objects and provides protection. Does not affect daily activities such as sleeping or eating. Adjustable Ring: The collar size can be adjusted. Build Confidence: When pets begin to adapt to this anti-collision device, they learn to trust it. This equipment helps pets rebuild confidence by guiding them to avoid hitting hard objects and protecting themselves.