It’s important to clean your binoculars regularly to maintain their quality and clarity—sand and grit can damage the lenses if you are not careful. Firstly, always keep your binoculars in a case when you aren't using them. Second, you need to make sure you do not scratch anything into the glass lenses. Use a soft lens cloth or compressed air when cleaning. Never use paper towels, your t-shirt, or any paper products, which can scratch the lens' protective coatings.