MONAGGIO Extra Ink Cartridges for Most Fountain Pens: 20 Refill Cartridges (5 Red, 5 Green, 5 Blue, 5 Purple) - Calligraphy, Fountain Style, Fine Point, Non-Toxic

They are easy to insert, ink flows well, the colors are of good quality.

Good quality and a nice set of colors. Excellent price.

These are so misleading. They are half the size of normal ink cartridges. I was very disappointed when I got the box.

Doesn’t fit any fountain pen that I have

Nice colors. Great value.

They fit, the colors are nice, they're wet... What else would you say?

The work we'll and the ink has nice color.

Both the description and the box state that they are International Standard size; however, this does not appear to be true. I purchased these for a Monaggio pen, but it had a lot of problems. I eventually got rid of that pen and kept the cartridges. I recently purchased a Diplomat Magnum fountain pen, that uses International Standard cartridges and so I thought I'd use these. I could hear them "click" into place, but they would just fall out again. The box is useless to me. (It's not the new pen; it came with one sample cartridge, and it works great.) They may work well on Monaggio pens, but they don't seem to be standard.