Schmeisser makes upgraded AR-15 buffer tube assembly. What makes it interesting to me is the approach of the company in product development. Instead of working on a development of a single aftermarket part, they have improved all the parts of the assembly (or subassembly). In this case, it is the buffer tube (receiver extension) assembly.
The core of this system is what Schmeisser calls SOLID Sleeve. It is a U-shaped bracket that replaces the endplate, extends rearward sandwiching the castle nut and “hugs” the lower receiver at the rear threaded portion. So this part reinforces arguably one of the weakest spots of the AR-15 design – the lower receiver and buffer tube connection point. The SOLID system also features a braided wire buffer spring.
The advantages of other SOLID parts are somewhat hard to understand due to lack of explanation by the manufacturer. As an instance, in the video below, Schmeisser doesn’t really point out how exactly their buffer and buffer tube are different or what does “pure rock solid steel” mean?
Nevertheless, I think this kind of designing approach is not a bad idea. From the customer’s standpoint, it may also be beneficial, because buying a bunch of upgrades (for any particular assembly) from the same manufacturer might be a better choice than buying from different manufacturers and hoping that they are all in spec and will work as a system.