For Steep, sustained descents, Trekking poles are a welcome aid to save the knees, add some stability and keep you upright. I received a set of the latest hyperlite poles from Black Diamond, their Distance Carbon Z Trekking poles. These are fixed at 120 cm length.
Easily the lightest ski or trekking poles I have ever picked up, these things have shaved grams everywhere. With the combination of a full carbon fibre composite layup, Kevlar string replacing traditional steel cable, and the high density EVA foam grips, these things feel weightless in your hand.
The Distance Carbon Z poles come with tiny trekking baskets and if you plan on using these for double duty as ski poles, then plan on installing some powder baskets, which may have to be rigged on since they are not readily compatible with any spare baskets I have seen. One handy feature is the groove in the basket that clips to the pole section when folded to help hold them together. Folded up these are just over 40 cm (16″) long.
The poles come with two sets of tips, a set of hard rubber tips and a set of carbide ones. The spare tips sit in a small pocket that is sewn into the retaining strap. The tips thread into the ends and are held secure with a detent-style folded feature in the tip socket that mates to the tip once threaded in with pliers. I question the usability of the rubber tips as any use at all on hard rock, road or sidewalk surfaces would wear these away to nothing since they are very small.
The EVA foam grips are extended below the main grip for fast hand position adjustments on steep or technical terrain. The grips use a thin, tapered adjustable webbing strap for your wrists, I personally never use straps, even when skiing so these will be removed for future use.
Extending the poles is very much like deploying an avalanche probe where the sections are held all together with an adjustable (synthetic) cable and all you need to do is let the sections fall loosely, grab the top handle and the portion just below the grip and pull them apart. The poles lock into place with a positive clip that is similar to how an umbrella stays open. This button is easy to push with gloves on. The internal cable length is adjusted with a plastic or CFRP barrel adjuster to get the tension right and to compensate for stretch over time.
The cable is covered with a clear-bluish soft plastic . This is the only piece that I can see getting abraded/cracking over time with extended use. With the cutting edge of ultralight gear, there are always trade offs. At a published weight of 290 G for the 120 CM length, The poles are available in 100, 110, 120 and 130 cm lengths.
I really like the combination of compactness, light weight, comfy grips and ease of deployment. I have not used them long enough to comment on durability, but based on what I have seen, I would recommend these poles. The poles come in a set of two and are listed with an MSRP of $159 USD on the BD website.