Handy tip - Here is how we use it. Put a "little" water in the bottom, not from the top! And by little, only a bit and allow the water to soak up unto the pad and sides. You will figure out just the right amount in a bit of time. If you put too much and push down you will be covered with water when it comes flying out, you've been warned. We found that out too the hard way when we started using these a long time ago.  Avoid the plastic side or holder with your soldering iron for obvious reasons, it melts. Touch only the sponge.

You get TWO of these!