Each collar is wrapped in fabric and then lined in a matching complimentary plain fabric, all of our collars have a polypropylene core for extra strength and double stitched in a high quality nylon thread, it is then finished off using a high quality plastic buckle. All of our collars are fully washable as we all know that dogs love to roll in smelly things! so should your best friend get their collar dirty, just pop it in a sock and throw it in the washing machine on a low heat quick wash and it'll come up like new! Size guides: Extra Small - Miniature breeds, buckle & collar width of 16mm,9-12 inch neck size. Small - Jack russel, cockapoo, bichon frise etc, buckle & Collar width 16mm, 11-15 inch neck size (please state if you would like a 20mm buckle and collar width instead). Medium - Springer Spaniel, collies, staffies etc, buckle & Collar width 20mm, 14-20 inch neck size (please state if you would like a 25mm buckle and collar width instead). Large - Labrador, german shepherds, short haired pointer etc, buckle & Collar width 25mm 19-25 inch neck size.