Aloha Dog Collars are made of an awesome nylon custom design! They are very strong and made for all-size dogs. The collars can be adjusted, but please measure your dogs before ordering. For the most accurate size, measure around your dog's neck where the collar would be, it's also a good rule of thumb to be able to fit in a couple of your fingers. If you feel your dogs is between sizes, go with the larger size! Small 10inch - 15inch around, with a .6inch band Medium 13inch - 21inch around, with a .8inch band Large 16inch - 26inch around, with a 1inch band Aloha Dog Collars are inspired by the beautiful island of Hawaii and we are so glad to share them with you.