I needed 20 gallons and when I called the sales representative gave me a great deal, I guess they offer quantity discounts. Very easy company to work with, product shipped fast. It works great on my driveway. I had a terrible issue with mold on one section that doesn't get a lot of sun. It has been about six months and I haven't had any signs of mold growth. I just bought more to seal my pool deck and patio. Thanks for the deal! Very happy I went with this product.