I went ahead and checked out the Hanna Checker's page, although it was an exercise in redundancy for me, as I just picked up an alkalinity checker after researching them there.
I love the fact that the Hanna Checkers do the reading of colors for you. They are small, well packaged, and the checkers and reagants are affordably priced. I use my new alk checker daily, and my phosphate checker every 4-5 days!