OPI Nail Lacquer, Natural Nail Strengthener, Clear Nail Polish, 0.5 fl oz. OPI Natural Nail Strengthener helps strengthen and protect natural nails. This nail strengthener dries clear and can be used under any nail polish. With high-quality formulas, fashion-forward nail polish colors and iconic names, OPI's heavily-pigmented Nail Lacquers are super rich, long-lasting, chip-resistant and deliver up to seven days of wear time. Each Nail Lacquer features OPI's exclusive ProWide Brush for flawless application. OPI has been revolutionizing the world of nail color and care since 1981 with our superior product quality, fashion-forward colors, iconic bottles and fun shade names! Our vast array of products comes in a range of colors to meet every mood and self-expression.