Pilot Hi-Tec-C Coleto Multi Pen Ink Cartridge - 0.5 mm - Black

These are generally smooth refills, though quality control lets a few rough ones out here and there. The plastic body and thin diameter means they run out of ink quickly, but such is the nature of the beast. If one is looking for a pen with larger writing capacity, he or she can pretty much say the same think about all multi-pen refills. Overall, these are great little refills, though I think the Zebra D-1 0.5mm gel refills are the best, and noticeably smoother.

it is very smooth, and the whole hi tec c coleto multi line is pretty awesome, but this refill runs out so quickly, it's hard to really like it. maybe a smaller line size would negate that effect somewhat, but mine barely lasted 10 pages (writing front and back, every other line).

Ink is great - very smooth - seems even smoother than regular hi-tec c line. Best pen I own for everyday use.