Ever tried sharpening a stone 'til it's worn down to the mm's? The Backing Plate allows for two things:
1) security and protection of any given stone, ceramic or natural
2) compatibility with the Stone Stage to secure your stone of choice and create access to the rest of the Nano Hone System or any industry standard holder
With rigidity and security, you can use your favorite stone until it literally approaches paper thinness. Multiple color choices allow you to color code your system and bring the stylish aesthetic of the Nano Hone System in to your kitchen or shop.