Expanding on the blog post from April 2015, there are two features unique to the Hillside Washer that allow it to function. The Locking Tab and the Spheroid Shape.
Steel Manufacturing Blog: Keeping it Steel
For the construction trade, plastic shims are an essential tool but care must be taken to assure they are rugged enough for the intended use. Before even considering the compressive strength of a plastic shim you must first ensure that is it should be solid with uniform plastic throughout. Lower cost hollow plastic shims are manufactured but do not deliver the strength or durability required for most construction projects.
Tags: Shims, Construction Shims, Plastic Shims