I thought this would be a good energy bag since the Lenzyne seat bags are so nice. It is a good size but the closure is really bad - just a simple flap with a small piece of velcro to attach it. This closing flap will gap open allowing the bag contents to fly out. I could not imagine putting something important like a phone in this bag.
I will search for a bag that either zips closed or has a larger closure contact point.