As far as aviation shears categorization goes, I only use the Midwest. Know, Milwaukee or similar scissors just don't fit. (ha) Seriously, if you're cutting air ducts or the like, any knife will do. If you are looking for something reliable that can cut heavy metals. Then you need the Midwest. 4 stars only because Midwest has gone down in quality over the years. They just don't do it as well as they used to. That still doesn't stop them from being the best.