Prismacolor Premier Coloured Pencils feature a thick, soft core made from brilliant, light-resistant pigments, to ensure smooth, rich laydown and colour saturation. The colours are easily blended, slow to wear, break-resistant, and waterproof. Each 3.8 mm core is enclosed in a round cedar casing that is lacquered to match the core. They†re vivid and intense in one stroke and subtle and soft in the next, making them perfect for any project, big or small. Smooth coverage and a wide array of colors to choose from make it easy to find a soft spot for these premium pencils. Manual sharpening is recommended for these pencils. Clogging can be prevented in electric sharpeners by periodically sharpening a graphite pencil to keep the blades clean.