Alfie Couture Designer Pet Accessory - Zak Spiked Collar This collar is the must-have gear for your big dog. Please note that this listing is for medium size - collar is 2" wide and best fits pets with neck size 18.25" to 21.5". Made of strong and durable PU leather. Light, elegant and comfortable. Feature nickel-plated spikes and studs and sturdy D-ring for easy leash attachment. Perfect for everyday walk and weekend party, or just making your pet look its best. How to measure your dog's neck size: measure around the neck close to the shoulder and allow room for a comfortable fit.