A common problem with installing prefabricated construction elements such as windows and door frames, especially if the building is old or the framing is not square, is alignment. And it's not only alignment, but also the issue of needing an extra hand to hold the frame in alignment while you fasten it. Or, if the building has settled, you may experience uneven gaps between the window frame and the jamb, and subsequent air drafts, because the frame is not level or plumb. Shims are a perfect solution for all of these issues. While wood shims have traditionally been made in an ad-hoc manner from a wedge of scrap lumber or available in a limited range of sizes that have to be trimmed on site, there's now a better option with Allfasteners' shim product range.
Today, Allfasteners offers these products, also known as packers (or "horseshoe" or "window" packers in a lot of instances), made from high-strength PVC, for rot-resistant properties. Or, for use in structural steel situations, such as blind-bolting during structural upgrades on cell towers and the like, galvanized steel shims are also available.