May 17, 2021 | By Drew Zieff Share now: Support us! GearJunkie may earn a small commission from affiliate links in this article. Learn more. Home » Climbing » Mountaineering » Petzl Fly Review: An Ultralight Harness for Ski Mountaineers, Alpinists, and Splitboarders The Petzl Fly is an ultralight harness that packs down to the size of a few Clif Bars, and is made specifically for ski mountaineers and alpinists. I admit, I belong to neither faction of ski mountaineers or alpinists, but I am a splitboarder tiptoeing into steeper, more technical terrain. This past month, I had ample opportunities to log time in the Petzl Fly during an expedition to