Princeton Aspen Synthetic Bristle Brushes - Flat - 12. Same Stiffness as Natural White Bristles; Next Generation Synthetic Brushes; Ideal for Acrylics, Oil Paints and Water Mixable Oils, Stiffness: 4 on 5. Best release of colour; Retains its shape for great control & best colour placement; Paint glides evenly off the synthetic hairs. Double Crimped Distinctive Matte Black Ferrule; Natural Wood Finish Handles; Lasts a Lifetime of Use. Perfect for use outdoor / plein air painting as well as in the Studio