I've actually been looking at these kinds of trekking poles for a number of years now. The early ones available here in Japan were far too flimsy and wobbly for any serious walking, so I never bought one. However, in the trail running community there has recently been a development of "trail running poles" that are very lightweight, made of aluminum, and fold down to a very small package. I bought one yesterday, made by the Japanese company Sinano. A couple of weeks ago I saw another one made by the ice axe manufacturer Camp, but I can't remember the name of the product. All of the trail running poles I've seen come in lengths of 120 cm, 115 cm, and 110 cm. My Sinano 120 cm pole weighs 140 g w/ basket, rubber tip, and wrist strap (My GG Lightrek 4 pole weighs 120 g w/ basket, rubber tip, and no wrist strap... so my pole is actually lighter). The Lightrek is distinctly stiffer, but the Sinano is plenty stiff enough for a tarp pole and much stronger than the thin wands that tent companies often supply with their tarptents and tarps.
Comparing the Sinano (right) to the LIghtrek 4 (left). The Lightrek is collapsed down to 90 cm. The Sinano, when folded is about the length of my forearm... 32 cm.
The LIghtrek opened to 137 cm... the length I use for my Duomid. The Sinano, opened, but not secured. You can see the non-stretch cord that holds the aluminum tubes together.
The Sinano when fitted together. It is now 120 cm.
The Lightrek when collapsed to 120 cm.
You pull this cord to tighten and secure the pole tubes.
The cord pulled tight and fastened. Because the cord doesn't stretch the pole tubes are tight against one another and there are no loose joints.
Someone wrote earlier that he finds carrying fixed length poles around on public transport a real pain. I agree. Though I really love my GG Lightreks, they are a nuisance on the crowded trains here in Japan, always hitting the top of the doors when entering the trains and buildings, and keep getting snagged on branches when they are stowed in my pack. I use only one pole when I walk, and rarely use it when I ascend and descend steep terrain, so being able to get the pole easily into my side pocket makes walking with a pole a lot easier. The only thing this pole might have a disadvantage with is when using it as a shelter support. Being non-adjustable means that I can't lift and lower the pole to suit the needs of the shelter setup. Also, 120 cm is too short for my Duomid, including with the pole extender. The pole tip is also too short to nest the pole extender, too, and would likely be unstable in strong winds. I'll be using this pole with my GG SpinnShelter (I use a short aluminum tent pole section for the back)