Plastic buckles have an ergonomic curve to them to fit better around the dog's neck. Buckles are strong enough to last a lifetime. All buckle collars include a D-ring and adjuster.
Martingale collars feature a snugging loop with a strong D-ring for leash attachment as well as a secondary D-ring that is suitable for attaching a tag. Secure construction eliminates "backing out" of collars.
Martingale chains work great on leash and/or leash/collar combinations when the user needs to remove them quickly. Great for agility handlers.