Product review (1 stars): Nice product that was poorly designed.. giving it a fairly short lifespan.
EDIT: I lowered this from 5 stars to 1 because it fell apart after 8 months. The plastic clips that hold the clear part on are only 1/16" thick and became brittle and broke off, making it useless. If you don't mind buying a couple of new ones every year, the following review still holds true.. otherwise stay away.

Easy to install, easy to use.

If you are like me, you pre-rinse dishes before putting them in the dishwasher, making it hard to tell if the dishes are clean or dirty. Simply slide this on either the top or bottom rack and you will always know at a glance if your dishwasher has been run.
When you wash your dishes, the blue button pops up.. showing you they are clean. When you empty the dishwasher, simply push the button back down. Easy as that!