It is called SHUR-LINE and it worked out so great. We used it in our bedroom/ktichen to save us from the hassle of taping the ceiling. We did enough taping with those windows and trim (ugh). Blue tape madness. So worth it!
The one thing about this paint edger is you have to be careful not to get paint on the little wheels, or too much paint on the bristles because then you have a nice 3" thick border/line mark on the top of your wall. (We have some of those in the bedroom if you look close enough.) I would recommend using two thin layers rather than one thick one. Overall, this tool saved us a ton of time and I'm so glad I found it.
This is the border of the wall and the ceiling, check out that line on the right. Awesome huh?
To use it, you just dip it in some paint (i used a paper plate) and you drag it across the top or bottom of the wall. It has little wheels that you press against the ceiling so it makes a nice straight edge.
Here you can see the top and bottom of walls lined with paint from the SHUR-LINE tool:
Have you ever used a tool like this? How do you paint the tops and bottoms of your walls? Do you have any favorite time saving tools?