OPI Mad as a Hatter is a clear base with small round micro glitter. It has a variety of colors. Silver, purple, green, blue, gold, red, and probably a few others as well. It is very opaque on its own, but I still used Wet n Wild Silvivor as a base to fill in any empty spaces. I absolutely love this polish. And the wear is amazing. It did not chip at all during three days I wore it. Barely any tip wear as well. I did one coat of Silvivor, two coats of Mad as a Hatter then two coats of top coat to even things out.
MAAH has become quite the hard to find polish. If you do stumble across it, the price tag is usually high.