SNOUT CIRCUMFERENCE SHOULD BE MEASURED 1-1.5” FROM THE TIP OF THE NOSE. IF IN DOUBT PLEASE SELECT SMALLER SIZE. Available in 5 sizes. Please use Sizing Chart for Size/Breed Reference, Snout and Neck circumference, and Loop size. For size XLarge the Loop size is 10"-17", designed for snout circumference 12.25"-15.25". Nose strap layered with a soft foam for added comfort. Made of soft strong high quality 3/4" wide nylon. Easy to use well designed durable head collar provides control to stop pulling, jumping, lunging. Allows freedom to pant and yawn.