A trigger/rest designed for the 2010 and 2018 models of Quark, Nomic and Ergo. It can be used as a lower hand rest by chucking away the smallest bit and tightening it up fully (may need padding out with a bit of old inner tube).
You can remove the trigger bit if you don't want it, leaving just the upper rest.
It could probably be persuaded to fit many other axes and will fit older Quarks but only in a fixed position. However, Petzl say that fitting it to anything other than the new Quark will invalidate their warranty. Internal diameter is ca 90mm.
Price is per single item, not for a pair.