Tool-less air box access is cool, but not if your bike’s air box becomes suddenly accessible during a race. We haven’t had this happen, but we’ve heard of the Dzus fasteners becoming unfastened on the 2014, 2015, and 2016 YZ-Fs because of rider’s legs catching them. Interestingly enough, it was a big enough problem that Yamaha changed the shape of the plastic on the 2017 air box cover so the D rings on the Dzus fasteners are more protected. But for older models, you can just swap the Dzus’s for standard 8mm bolts. They aren’t tool-less, but they are leg proof.