This Absolutely Clear Scuba Mask Defog is a wax style defog that will last all day. If you're going on multiple dives throughout the day, this is a perfect defog to use so that you don't have to keep reapplying and you can use all that valuable time checking your other gear or enjoying the view. Apply a small amount to your dry mask lens, then buff with dry cloth or towel. One application can work all day.