The “gizzmo” is a specially made piece of molded plastic that fits in your swimming pool skimmer during the winter or the off season to protect your swimming pool skimmer in two ways.The pool skimmer gizzmo will protect your swimming pool in two different ways. The gizmo is designed to stop the skimmer from breaking from ice expansion. 
The pool gizzmo is also designed to plug off the bottom of the skimmer so that water can not enter the skimmer plumbing. The swimming pool gizzmo comes in a few different sizes as well as colors. The shorter gizmo is made for above ground pools and small skimmers. The Ultra gizzmo is made for deep skimmers. The original gizmo comes in green, however other brands will come in colors such as blue and black.
Here is how to remove your swimming pool gizzmo:
Remove the skimmer cover:
The first thing you will want to do is to remove the skimmer cover. Sometimes the skimmer cover will be secured by two flat head screws. Once the screws are removed you can stick your finger into the whole and then pull up on the skimmer cover to remove it. If the skimmer cover is stuck you may want to tap on it a bit and try again.
Removing the pool gizzmo:
To remove the pool gizzmo you will want to make sure the skimmer cover is removed as we described above. Now you will place your hand on top of the gizzmo and turn it counter clockwise a few turns. If there is water in the skimmer the gizzmo will pop up in the water because its full of air.
Replacing the pool skimmer cover:
Once you have removed the pool skimmer gizzmo you will now see some air bubbles in the skimmer if you have water in the pool. This is caused by water rushing into the plumbing of the swimming pool. Once the air and bubbles stop you can place your skimmer basket into the skimmer. Now that the skimmer basket is in the skimmer you can place the skimmer cover back on to the skimmer.
[...] basket so you can blow the water from the swimming pool lines. You will also have to insert a pool gizmo and plugs inside of the skimmer as well. If the basket was in the skimmer it would only be in the [...]
Small Note to anyone removing the gizmo:
If you unscrew the gizmo from the skimmer and it feels like it is full of water then the gizmo is no longer good. Once the gizmo is filled with water this means that it has cracked somewhere and will no longer protect the skimmer in the winter. The solution is just to replace the gizmo before the end of the pool season so you will have a new one for the pool closing.