The core breaks as soon as you write with a little effort. I bought five books, but both thrown away because they are not usable together. I purchased a different item at a later date, but I think that it is a defective item because it can be used without problems.
I always repeat. Since the eraser of the mechanical pencil is stored in the mechanical pencil body, there is no cap and there is no worry of losing the cap. All of our company 's Flower, this is a loyal user of this pencil. I will repeat in the future.