OPI Top Coat is a clear, high-gloss protective lacquer formulated with acrylates copolymer and cellulose acetate butyrate film formers, applied as the final step over dry OPI Nail Lacquer color to seal in shine and help resist chipping and smudging.
It's built for OPI's regular (non-gel) Nail Lacquer system: after two coats of color, one coat of top coat is pulled over the tip of each nail to cap the free edge, which is where most chips start first. A small violet pigment in the formula helps keep the finish from yellowing over time.
This is a solvent-based lacquer, not a gel or UV-cure top coat, so it air-dries and should be applied in a ventilated space and left to dry fully before nails are exposed to friction or water.