These Tarte Clay Pots come in a lot of different shades, and can be used with your preferred brush in whatever application you desire. The magical part though is how well they dry down and lock in place for the long haul. They're a creamy gel consistency that is easy to blend and apply, but then after a few minutes, (not a race against the clock,) they set and are budge/waterproof. Cobalt in particular is the perfect bright blue with a subtle shimmer that I like to apply with my Luxie 215 for eyeliner or 221 for a smudged look. They can be opaque immediately for a crisp wing or built with additional layers for more intricate editorial styles. Or, they can even be sheered out for eyeshadow, where the dry-down effect then gives you buildable colors that will play well together without being pushed around. It's not a product I gravitate towards all the time, because application is more time consuming, but when I do use it, I love the result.