This is a size S visor for long-nosed dogs. I purchased this visor to protect my beloved Italian Greyhound's eyes from glaucoma, especially to prevent UV damage when going outside. I measured my Italian Greyhound's head and determined that size S would fit, so I bought it, but it was a little too big and didn't fit. For Italian Greyhounds, it seems safer to ignore the measurements and choose the TOY size... I've also seen similar size incompatibility cases with other sellers. I think it's best for those who have experience using this product to purchase it again. If you are considering purchasing this, it will probably fit a dog one size larger than the size described. Please check the seller's website for more details. I think the design and function of this product are truly excellent and unlike anything else. The product has only been tried on and has been stored at home for a long time. Please note that returns due to a difference in image are not accepted for either product.