Comments about Zebra® Sarasa® Retractable Gel-Ink Pens, Medium Point, Red, Dozen:
Write with the tip face down.
It doesn't write well horizontally, or on textured surfaces.
For example, if you're using it with an easel to cross things off your to-do list, the writing quality sucks - it looks like a pen that's running out of ink.
I think I threw out a few of these, before I figured this out, that it needs gravity to work. They should put this on the box as instructions.
Writing with them face down on a pad of paper (cushiony surface) or a hard smooth surface vs. a textured plastic surface, also gives better quality writing.