Features: - 20Pcs SK-5 high carbon steel blades, 10pcs in 1 storage box, sharp and hard - Aluminum body handle with safety cap, fits with all standard craft knife blades including Xacto Knife - 15cm Steel ruler with thickness of 0.7mm, one side is metric system and one side is imperial graduation - NineSea 5 layers high quality PVC Cutting board,Double sided usage,Size : A4 (22 x 30cm), 3mm thicker,without any smell. Package Include: 1 x Precision knive 40 x NO.11 Blades 1 x Steel ruler 1 x A4 Cutting board How to replace the blades: 1.Unscrews at the tip to unravel the blade, take out the dull razor you have used for a long time. 2.Retighten it after replacement and lock the new blade in place. 3.Please be careful not to be scratched when replacing the blades. Notice: Please cover the precision knives after use, and keep them away from children. Please watch out for your fingers when replacing blades to avoid any cutting and scratches.