This product is a hand-crafted replacement refill for Cartier ballpoint pens. Genuine refills are currently very difficult to obtain. Are you looking for a Cartier refill? Compatible part number: VXRB0211. The base is a Mitsubishi SK-8 (0.8mm) black ink refill. Compared to overseas replacement refills, it achieves stable quality. We have confirmed that there are no issues with installation. Each item is carefully processed, but please understand that it is a handmade product.