This is a 4cm wide half-check collar for long-necked dogs like Whippets. It is not adjustable, so if you use a half-check collar, please be sure to compare the following leather and chain sizes with your current collar before purchasing. This is a one-of-a-kind finished product, so please contact us if you need a different size. Leather width: 4cm Thickness: Approximately 4mm (may vary slightly depending on the leather) Head circumference: 32.5cm ● Leather section size: Approximately 23.5cm ● Chain size: Approximately 12cm (The reason the total does not equal the ordered head circumference is because the chain and leather overlap, and it is calculated based on the size that can be put on and taken off the head.) Please contact us if you are unsure. ++++++About Extra+Heavy+++++++ We have many other items for sale, so please take a look. Extra+Heavy is a handmade collar shop that specializes in custom-sized collars, including half-check collars and leads, mainly for bulky collars for breeds like Bulldogs and long-necked dogs like Italian Greyhounds. Our sites include Rakuten Shop, Yahoo! Shop, and our main store. * You can find Extra+Heavy by searching for "collar studs" on Rakuten Shop and Yahoo! Shopping Mall.