What is the expected life cycle of the tapered sleeve or friction pad in the WD Hitch anti-sway housing? What is the material?

We warranty the friction or brake material for life, but do not foresee ever having to replace it due to wear. The material we use is similar to the material used in auto brake pads, but in its lifetime will only be subjected to a tiny fraction of what a car's brake pads would be subject to. Putting it another way, our engineers figured out that if you were to compare the amount of pressure our friction pad is typically subject to over a span of 30 years compared to how much a typical car's brake pad is subject to, it would be the equivalent of braking hard a few times. Keep in mind that the only wear it can really be subjected to would be when the tow vehicle makes a turn – there almost no friction exerted when it is traveling straight. If for some strange reason it should ever wear out, we will replace it for free. We currently have no part number as we do not see needing to replace it.
On a side-note, we currently have a local Weight Distribution owner who has over 11,000 miles of travel with his weight distribution unit, and as of last month we could not detect ANY wear on his friction pad.