This Milan Capsule eraser refill, sold in a set of 3, is compatible with the eraser pen from the same line, allowing you to replace the worn-out core without having to buy a new complete stick. This solution extends the lifespan of the original product, making it a more economical and sustainable option in the long run. A practical Milan refill for those who already own the Capsule eraser pen and want to continue using it with the same effectiveness.