The Dr. Grip pen comes in a lot of different versions, one is as a gel pen, another a Mechanical Pencil. They are quite different, appart from being different types of pens they also have different tips, grips shaped in different forms, and different barrels. They don’t even have the same ‘look’! There’s the Japanese Dr. Grip shaker, wich tip is used for the Dr. KT. The European Dr. Grip with a futuristic look, with a smaller tip then the Japanese one. The Dr. Grip with a plastic clip, wich also has the tip needed for Dr. KT, and the Dr. Grip with a metallic clip. Dr. Grip is available in a lot of countries, but not always in the version you need.
Well known Pen Mods using Dr. Grip: