A brush developed, tested, and perfected by celebrity makeup artist Ariel to seamlessly blend foundation. Brush Formulation: Liquid Brush Coverage: Buildable Bristle Type: Synthetic What Else You Need to Know: Using his expertise, Ariel created this Morphe X Ariel A24 Signature Foundation Brush that features densely packed bristles and a rounded tip. The densely packed bristles work like magic to blend seamlessly, he says. Without it, the looks I create wouldn't be my signature looks.