Cleaned after each wear!!! Compatible with 38mm/40mm/41mm S/M: 5.1"-7.1" (130mm-180mm) sized wrists! Premium Material: Made of high quality silicone, very soft, lightweight, durable, waterproof, breathable & comfortable. Unique air-holes design: Unique air-holes design makes sports easier then ever, prevent sweating of the wrist during exercise, and allow your skin to breathe freely. More breathable & lightweight. Perfect for workout, swimming, climbing, hiking, traveling etc. Fit for most wirts. The size can be adjustable by the air-holds.