Multiliner SP pens feature a durable aluminum barrel, are refillable and have replaceable nibs. The waterproof, pigment-based ink will not bleed into COPIC markers. In a variety of sizes for all your drawing needs. Refill ink cartridge A is for pen sizes .03mm, .05mm and 1mm. Refill ink cartridge B is for pen sizes .2mm, .25mm, .3mm, .35mm, .5mm, .7mm and Brush.