I've been using Nail Tek Intensive Therapy II for years on my thumb nail that has a split down the center of my nail about halfway to the base. I brush a coat or two on every day and it protects and strengthens my nail to help prevent it splitting further. I can't wear nail polish because it tends to make my nails break off but Nail Tek Intensive Therapy II doesn't affect my nails like regular polish does. A few years ago I went to a salon and had an acrylic nail put on just the one nail since it was impossible to keep it from splitting further and further. I kept the acrylic thing going for about a year and decided that was enough. When the acrylic was gone my nail had grown out and was not split but still very fragile and thin. I started back with daily application of the Nail Tek Intensive Therapy II and have continued to use it faithfully. My nail continues to be healthy looking and I don't have to be embarrassed of a split nail. I'm a loyal fan of Nail Tek!