The dogbone is aluminum, the stainless steel Slic Pin mates to a flat surface on the aluminum body. Again, it looks like the original HH's but very different. If you put an aluminum biner next to the narrow and sharp edges of the hardened body of the HH it will not last long, thus the steel biner. If you put a Slic Pin shackle in a HH1 or HH2 it hangs up on the edges and is very difficult to release. Taking out the Slic pin on the HHx it is a couple easy pushes and a twist.
Great work on the new device! I was considering buying an HH2 this year but planning to get one of these instead. Pretty much just being a rec climber these days the weight savings alone would be nice. Even though I'm not in the industry any more, all the equipment innovations in Arboriculture these days is really exciting to watch!