The anti-collision ring can adjust in height and position. S = ring diameter 22CM (suitable for 4-10KG), neck circumference 28-40CM, chest circumference 32-45CM; M = ring diameter 33CM (suitable for 13-20KG), neck circumference 32-45CM, chest circumference 36-50CM. High-Quality Materials: Blind Dog Harness is made of aluminum, SBR, and foam material, odorless, reusable, and durable for long-term use. EASY TO PUT ON - This halo for blind dog comes attached to a vest harness so your pet can wear it easily. The Blind Dog Harness Guiding Device is adjustable and secured by touch fasteners to ensure that your dog is comfortable as they learn to adapt to their limited vision. The pet ring is adjustable to fit your pet's size and is easy to wear. Suitable for small or medium cats and dogs, helping blind pets become familiar with their surroundings quickly and safely. Lightweight design does not interfere with daily activities such as sleeping or eating. The anti-collision ring is made of aluminum, SBR, and foam material, odorless, reusable, and built for long-lasting use. Protect your Pet: Blind Dog Halo Collar helps blind pets stay safe and move freely, prevents collisions with walls, furniture, and other obstacles, and reduces the risk of painful bumps.