It is the best adhesion inducer on the global market today. The product is not acid and assures a perfect adhesion of gel to the natural nail. PRE OPTIMA aids adhesion between the natural nail and gel. The adhesion, in the first phase, does not involve the metacrylic acid and is therefore less invasive for the natural nail. It is not a PRIMER but a gel that has the same function. Curing 2 minutes.