Union Jack dog collar, Large dog collar, Red dog collar, Blue dog collar, boy dog collar, Girl dog collar, Dog collar, cool dog collar, Adjustable collar, Unique dog collar, Handmade dog collar, St Georges dog collar, Union Jack Pattern Medium Dogs - Neck 11" to 18" Large Dogs - Neck 16" to 26" 25mm 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.