a fully adjustable strap ,It suits your pet dog at different stages of growth.Multi-Function:Prevent Dog biting, Barkingand,Chewing and other problem.Adjustable Design: The muzzles have adjustable strap and quick release buckle,making the best size for your doglight and breathable, Adjustable strap with release buckle, easy to put oncolour:blackMaterial:nylonsize:S(Elastic Belt:39-68inch; Depth:12-23inch; Mouth Circle:48-56inch);M(Elastic Belt:39-94inch; Depth:16-33inch; Mouth Circle:52-7inch);L(Elastic Belt:39-94inch; Depth:24-39inch; Mouth Circle:62-86inch);XL(Elastic Belt:39-106inch; Depth:31-53inch; Mouth Circle:7-11inch);XXL(Elastic Belt:39-11inch; Depth:33-53inch; Mouth Circle:86-134inch);Front ring size: 13cm 15cm 165cm 18cm 195cmPackage Contents:5*Dog Mouth CoverOnly the above package content, other products are not included.Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.