Use The Power Of Air To Shim Your Windowshttps://www.tool-rank.com/media/listing/photos/thumbnail/300x300s/6e/0e/ed/WinBag-78-1452643889.jpg
When installing windows or doors you need to use shims to help hold the frame level and plumb. Typically you would used the classic wood cedar shim or you would use the newer plastic or composite shims. But now there is another option on the table, air shims. The air shim I am talking about is called a WinBag, and it is actually a small inflatable bag that expands with a few hand pumps of air to fill gaps ranging from 2mm to 50mm (0.078" - 1.968"). Once you use the WinBags to get your project level and plumb, you can then fasten it to the wall, remove the WinBags and fill the gaps with expanding foam. The WinBag has a weight load rating of 100kg (220lbs), so it shimming and moving possibilities are endless.
I can only seem to find the WinBag at UK stores, but it looks like it could be a re-branded Steck Easy Wedge, which is most commonly used to wedge open locked car doors to help gain entry. The Steck Air Wedge can be found online for around $30. Update: The WinBag is now available in the U.S. - Amazon