Melbourne climber, Tim Broadbent, who conveniently has a brother in the army, came across this military-style belt bag: the Maxpedition Rollypoly Dump Pouch - yes it's a bit of a mouthful but once you see the video below you'll forget about that and immediately find a use for one of these babies on your harness.
Tree climbers are always on the look-out for innovative new ideas from other disciplines.
The closest one-handed harness bag to the Maxpedition Rollypoly that we know of is the Yates Hip-It. But there is one major difference - the Hip-It doesn't fold up small when not in use.
The MRDP folds up so small you'll almost forget you have it on your harness according to Tim (Tim has two of them: one on his Petzl Sequoia and one on his Treemotion) - would be great for SRT kit, in-tree throwline, rescue fiddle blocks or anything else you need to carry into the tree.