DIMENSION: 3 sizes available: S-3.0mm50cm, weight 105g; M-3.5mm55cm, weight 145g; L-4.0mm60cm, weight 345g (length not including the 2 O rings). Nice silver color. It is suitable for medium and large dogs, and very runaway dogs. MATERIALS: Made of good quality steel, well chrome plated for strength. The surface of the chain is perfectly smoothed to avoid hurting the animal. RESISTANT: The collar is durable thanks to its chain structure, very resistant to bites. The chrome layer makes the collar waterproof and rust resistant. Attention, do not leave the collar in water or rain for a long time, dry it with a dry cloth as soon as possible after getting wet please. DRESSAGE: Good design for training and training. other daily activities. The idea of the choke collar is intended for the training of a runaway dog by ensuring your control when the dog pulls suddenly. INSTRUCTIONS FOR USE: The collar is composed of a chain and 2 identical rings O-shaped at the ends of the chain, its use is a little different from classic necklaces. Attach one of the rings to a leash, with the remaining ring, insert the chain into this ring, then slide it, this gives you a slipknot, pass the chain around your pet's neck. Please see image 5 (How to use) and also a video in the customer comments to better show the handling. Size (diameter of ring O: 3 cm) S: chain diameter 3.0mm, chain length 50cm, weight 55g. M: chain diameter 3.5mm, chain length chain length 55 cm, weight 100g. L: chain diameter 4.0 mm, chain length 60 cm, weight 150g. Usage: INSTRUCTIONS FOR USE The necklace is made up of a chain and 2 identical O-shaped rings at the ends of the chain, its use is a little different from conventional necklaces. Attach one of the rings to a leash, with the remaining ring, insert the chain in this ring, then slide it, this gives you a slipknot, pass the chain around your pet's neck. < p>Maintenance method Do not leave the necklace in water or rain for a long time, dry it with a dry cloth as soon as possible after getting wet; Do not use corrosive detergents to wash it, wipe with a damp cloth, then dry it naturally. Ideal for training The dog who wears a choke collar from his youth, if in a good way, will form a good habit of obedience growing up. In normal case, the dog doesn't feel any sense of depression and doesn't even feel the collar itself. The collar tightens quickly once the dog runs too fast or pulls sharply. Warning A choke collar must be put on the right way so as not to disturb your pet . This "common sense" depends on the habit of the animal when it goes out with you, so you have to check if your dog prefers to walk on your left or on your right. The choke collar is not recommended for dogs with respiratory problems, for whom a harness serves much better. If your dog is used to a harness, it is better to use a regular collar first, and then gradually try a choke collar.