I love Frenchie dog collar, Medium dog collar, Small dog collar, Smart dog collar, Girl dog collar, Blue dog collar, Red Dog collar, Boy dog collar, Adjustable collar, Unique dog collar, Handmade dog collar, Smart dog collar, French Bulldog, Boston Terrier Small Dogs - Neck 9" to 15" Medium Dogs - Neck 11" to 18" 20mm Width All Collars can be altered to be smaller. If you want a collar in a bigger size check before placing an order. Since Dogs come in all shapes and sizes, we recommend you measure your pooch so you get the right size. We recommend you use a seamstress tape measure. If you don't have a seamstress measuring tape, mark the measurements on a piece of string and measure against a ruler or rigid measuring tape.