OPI's Start To Finish ​Formaldehyde-Free is a 3-in-1 formula that delivers the benefits of a top coat, base coat and nail strengthener. Infused with Wheat Protein and Calcium, the high-performance treatment can be applied before nail polish to prevent staining of natural nails, after nail varnish for mirror-like shine and protection against chipping, or as a strengthener to promote harder, stronger nails. Combining all three tasks in one convenient bottle, you can expect salon-worthy results with effortless, easy application. Formaldehyde-free.