"100% Waterproof. Integrated barrel lock with two keys. 4 different size base rings for optimum fit. Ergo shape for a more comfortable fit against your body. Two piece contruction to reduce pinches. Dimensions: Inner diameter: 1.29" / 33 mm. Total length (top side): 3.27" / 83mm. Total length (bottom side): 1.77" / 45mm. Rings: S: 5cm / 1.9" x 4cm / 1.5" M: 5cm / 1.9 x 4.5cm / 1.7" L: 5.5cm / 2.1" x 5cm / 1.9" XL: 5.5cm / 2.1" x 5.5cm / 2.1""