Hemp Martingale Dog Collars-M(14_20)-RED by Earthdog Hemp Martingale Dog Collars. Our non-slip Martingale Star Dog Hemp Dog Collars feature triple layer 100% hemp canvas construction; contoured martingale closure and the most distinctive quality trimming available. When the dog tries to pull their head out of the collar the tension on the leash pulls the small martingale loop taunt which makes the large loop smaller and tighter on the neck - preventing escape. When adjusted properly the dog is never choked but the collar stays snug around the dog's neck (just behind the ears) until the pressure is released. Unlike nylon and other synthetics hemp softens with wear making these collars extremely comfortable for your dog and because they're machine-washable they're hassle-free. Please click on our Resources page for more training info. Sizing: Width 1 in. Fits 14 to 20 inches.