Being in the Military most of my life and wearing Government issued combat boots that never fit properly, my feet now are a total wreck. I couldnt get the locks for the plastic covers to go in so I gave up on them and bought some stainless screws, washers and locknuts in sizes appropriate for the covers (#10 or #12) to use instead. Id had to put about 20-30 hours in. Absolutely love the purple ?? I wish that the carabiner was metal, but the one that comes with it is heavy duty feeling.  and a neewer microphone suspension arm  The zipper isn?t great - very stiff and crooked. Fit PERFECTLY. May have gotten a bad pair but for 250$ I think every pair should be a good pair, so I took the refund and will be trying another model or brand. I ended up having to take them off due to the strap really rubbing in my feet. I cannot speak for the technology involved, but this is a difference between this product and others.