Silicone Brushes – Colour Shapers BLACK are excellent tools to sculpt and add incredible effects when modeling and sculpting with different putties, clays and fimo. They are somewhere between a brush, a palette knife, a modelling tool and your fingers. Easy-to-clean and long lasting. Non absorbent. This is the firm version of the black silicone brushes. They would be twice as hard as normal white brushes, and half than extra firm. This set is coming with 5 different brushes with 5 different tips with 6mm length by 3 mm width - SIZE #0 Each brush in the offered sizes have different uses depending on the putty we want to use. Nevertheless from Green Stuff World recommend to use White tip brushes for soft putties, and SIZE #2 for harder materials such as Green Stuff, Super Sculpey Firm among others. This is a question of taste and preferences, but at the end and as your sculpting skills get better you will finally end up having 1 set of each.