Boots are easy to put on with expanding side seams. Two easy to adjust velcro closures. Neoprene at closures cushion dogs foot. Water resistant and durable. The sole is made of Toughtek. Boots are 8 mm thick abrasion resistant non-slip thermoplastic materials pliable and ideal for indoor and light duty. How to measure width: Place dogs foot on paper and press on top to spread foot like when walking. Mark the sides. Width of foot should be smaller than the size of the boot. Sizes: Petite 1 1/4 width XSmall 1 3/4 width Small 2 1/4 width Medium 2 3/4 width Large 3 1/4 width XLarge 4 width.