Made of soft silicone material, safe and healthy. Keeps octopus regulator in place. Allows regulator to be positioned under the chin. Convenient and portable to use. Essential accessory for divers for deep diving, snorkeling, and other water activities. Material: Silicone Size Options: - Size 1: Perimeter - 62cm (24.41 inches), Diameter - 20cm (7.87 inches), Small ring - 5cm (1.97 inches) - Size 2: Perimeter - 72cm (28.35 inches), Diameter - 23cm (9.06 inches), Small ring - 5cm (1.97 inches) - Size 3: Perimeter - 82cm (32.28 inches), Diameter - 28cm (11.02 inches), Small ring - 5cm (1.97 inches) Package Includes: 1 Piece Diving Regulator Necklace Note: - Please allow slight measurement deviation due to manual measuring. - Due to monitor display differences, the actual color may vary slightly from the image.