TWSBI Diamond 580AL Silver Fountain Pen nib B Our ever popular 580 now has aluminum milled parts (Grip, connector, piston rod) Piston filler type fountain pen. Easy twist to fill, no hassle. 580 has improved the smoothness of cap thread turning 580 has increased ink capacity, about 30% more than 530 Comes in EF, F, M, or B nib sizes. Please look at other listings for different size