This waterproof bag has an airtight seal that prevents the re-entry or release of air and micro-organisms such as dust and sand. This sturdy plastic pouch fits inside a SPIbelt® or an SPI Messenger Bag and works with your smartphone touch screen! The aLOKSAK® is the perfect SPIbelt accessory for kayakers, stand up paddleboards (SUP) and obstacle course racing (OCR) such as Spartan Race or Tough Mudder.