I like that it works. Lol. It’s good ink. Works as stated.I wish pilot would just come out with a larger bottle of ink & refillable cartridges tho. Also, it would be nice to get some neon/uv reactive ink colors added to the selection.I gave these to my husband for his birthday and he loves them. He is really into calligraphy right now and he loves having so many color options.For the price, you can't really beat this ink for your Pilot Parallel Pen. For just under $5 you get 12 different colors to play with. And they're not just for Calligraphy. I use mine for Calligraphy, yes, but I also use it for my Art. I love my Pilot Parallel in my Art. Art Journals, Handmade Cards, pretty much anything I design... yep, this ink is killer.Yes, you *could* refill your own pen - and I have, for a few reasons. For instance, I like India Ink and sometimes I want to use that. But, these are SO much simpler, so much easier to use then refilling your own. Let's face it, refilling your own takes patience. Time. Patience. And it can make a real mess. ;) These, you simply unscrew the old one - pop in the new one. Wallah, your done. Easy as pie. (Be sure to clean your pen in between colors.)What I love:I love how smooth these colors are. It's like ice-cream. They're so creamy they just glide right on the page. In a way, they remind me of markers. Like Markers, they're smooth and thick. Bold and beautiful.I love how quick and easy the cartridges are to change.I love how vivid the colors are.I love the price. Bottled ink can be really expensive, so when you compare the difficulty of refilling the cartridges, versus using these refills at this price - I don't feel like I'm losing.I love that you get 12 different colors.I love that if you have 2 different pens, you can get color gradation.What I don't love:I don't love that you can't store opened colors. At least not very easily. (Another reason I've refilled my own.) The best you can do is keep them upright in an airtight container - (and it still may not work). Pilot, however, does not recommend this. (Of course they don't.)I don't love how sensitive the cartridge is. If you apply a tiny bit too much pressure while squeezing them when you're loading a new cartridge to get the ink to flow into the nib, you chance causing a leak in the cartridge, or blowing ink everywhere through the nib.I don't love the price. I know, I just said I did. But when you see how tiny the box is, and you really, really think about what you're getting - inks expensive!Some Tips:Like Markers, these inks will bleed when used with thinner paper. So, be sure to place a drop sheet, or the likes, beneath your work, or use thicker paper to prevent bleeding.These inks do NOT dry quickly. Therefore, be careful not to drag your hand, pen, or anything else through your work before it is dry.I recommend this for anyone who has a Pilot Parallel Pen. If you don't have a Pilot Parallel Pen, what are you waiting for? Go get one. You can find my favorite, the 3.8mm (green) here: I love writing in calligraphy, especially in different colors!These are top self ink cartridges with spot on colors.I recommend these ink cartridges.It’s nice to find this refill pack with 12 instead of 8 or 10 colors, where multiple color options or refill cartridges would just all be black ? - to find 12 *different* colors is a rare and welcome sight! The ink colors are gorgeous and the lettering is so smooth and easy and clear and so on. Love this stuff!!the variety is awesome...wish I could buy 12 of the same colour (you can in black and blue but not other colours.)Worth the moneyOriginal, quality productGreat change from the standard ink colours to brighten my day!Super product.Good range of colours, ink quite dense, very good.