I used this for my flagstone around my pool. The pool is 16 years old, I have lived here for 5 years. and the flagstone still looks great. I was told by my pool guy to seal the flagstone every year to prevent it from flaking and splitting. I researched several products and found this was the best in what I found during my research. It says it is good for 10 years or more, but I have applied it every other year just to make sure I am protected. I use an inexpensive pump sprayer from big box store and it works great and is very easy. Water beads up so I know it is working and is not slick for the swimmers safety.