Thank you for viewing! I've modified the rubber grip section of a Jetstream 4&1 multi-pen with a carbon fiber replacement. This is a straight shaft. This listing is for the metal grip section and wood parts only; the pen body is not included. There is no warranty. If it breaks, please reattach the original rubber grip. I will wrap it in bubble wrap and ship it via Nekopos (a Japanese postal service). Shipping will be on weekends due to my schedule, so please allow some time. For those who understand handmade items, how about it, including shipping? Carbon fiber is a lightweight and durable fiber made by carbonizing acrylic fibers, petroleum, or coal at high temperatures. Although it is a thin thread on its own, it is used in combination with resin to create composite materials such as "carbon fiber reinforced plastic (CFRP)" and is used in a wide range of fields such as aircraft, automobiles, and sporting goods. Its main features are lightness, strength, and high heat resistance and corrosion resistance. Thank you for viewing! I love stationery and use Jetstream and Dr. Grip 4&1 pens. I dislike the deterioration of the rubber, so I started making them for myself using scrap wood from famous trees that I had collected. You can customize these practical pens to your liking, just like changing your smartphone case. I hope that my handmade wooden pen shafts and wood parts can be of some help in your daily work, study, tests, qualifications, and entrance exams. For those who like handmade wooden pen shafts, those who like the works of wooden shaft workshops such as Craft A, Nohara Kougei, Koubou Setsu, Kobuta Koubou, and those who like multi-function pens such as Jetstream 4&1, Dr. Grip 4&1, and Pure Malt Premium 2&1, how about it? I use famous trees such as Karin Kobu, Karin Kouhaku, Snakewood, Pink Ivory, Desert Ironwood, Kurogaki, Kurogaki Peacock Grain, Beniki, Ebony, Rosewood, Sandalwood, Palo Santo, Briar, and Rosewood. #jnsm