We love these pencils for their soft cores, allowing more control over how much color you are applying in one pass and easier blending.
From the manufacturer:
Prismacolor Premier® Soft Core Colored Pencils feature soft, thick cores that are perfect for layering, blending, and shading. These colored pencils are vivid and intense in one stroke and subtle and soft in the next, making them great for both beginners and professionals. Available in a wide array of rich, vibrant colors, these high-quality colored pencils help add enhanced impact to artwork.