With so many nail polishes available today it can be overwhelming when trying to choose the best one. Why do I choose to use OPI Nail Polish. I have used many different nail polishes available in the nail industry. Aside of fun quirky names, I have discovered from experience that OPI nail polish is one of the most durable and longest lasting nail polishes available. OPI nail polish stays on in some cases for at least up to two weeks! Since 2006, OPI has reformulated its entire line of Nail Lacquers, Nail Treatments, and Nail Hardeners to eliminate DBP (dibutyl phthalate) and Toluene.