The Clear Tester has transparent key caps so you can see the type of switch underneath. This is great for technical aficianados who prefer to "look under the hood". The Clear Tester contains six different switches:
Super smooth (red silent)
Heavy smooth (black)
Heavy clicky (green)
You can also get a Clear Tester as part of the Office Collection.
In this model the Green and Silent Red switches are by Cherry. The other four basic switches (red, blue, brown, black) are by Greetech.