Pilot FriXion Biz Point 04 Erasable Gel Ink Pen Refill - 0.4 mm - Blue - Pack of 3

this pack of blue ink refill is a good deal. It can also fit into the "Pilot FriXion Ball Knock Retractable Gel Ink Pen - 0.5 mm "

you can save a lot when buying this kind of refill pack.

again, good points to buy pens on jetpens is:free shipping over $25, variety choices of pens; fast shippment.

but the price here is much more expensive than other website in US or in other countries.