The secret to the Cosmotop Spin's incredible water holding capability is a blend of 5 different fiber diameters. Thicker fibers placed on the outside work with thinner fibers in the middle to trap and hold water & color. These varying diameters create a fine point, stable shape, and energetic spring. They feature an ergonomic handle for maximum painting control. Great for watercolor, Gouache, Inks and acrylic.