Super Grip G Ultra Fine Retractable Multicolor Ballpoint Pen Series... The 2 color and 3 color pens have a shaft diameter of 0.4 inch (10.7 mm), and the 4 color pens have a shaft diameter of 0.4 inch (11.8 mm) and a very fine body. It is slim enough to fit in your bag or notebook pen holder without stress.. Ink Color: Black, Red, Blue, Green Ink Type: Oil-based Ball Diameter: 0.7mm Refill Part Number: BKRF-6F Other colors are used in the detailed images. Size: Height = Width = Width = 144 mm Thickness = 10 mm Product Color Tenduity: Purple