I didn’t realize how tiny this converter was until I had it in my hand. After looking at it and laughing I opted to use the standard ink cartridge that came with the pen.
I usually just go with cartridges for my Kaweco Sports, but I decided to try out their converter when I ordered the Iridescent Pearl, and I'm glad I did. Requires a little extra effort to get it to engage properly with the feed--takes a bit more pressure than you might be used to with a standard converter, but it *will* stay on if you apply firm but gentle pressure until it snaps in there--but once you surmount that hurdle your ink options are increased exponentially. Combine that with the low price and there's really no reason not give it a try if you're a fan of these pens.
I ordered this piston as it was recommended for Kaweco Sport pen, but it does not fit in the pen properly and keeps sliding around, not locking in.