I broke a pair of Native sunglasses I'd had for nearly 6 years and decided that I wanted to find something really nice for my next pair. I spent dozens of hours researching brands, lens colors, lens materials, etc. I'm an avid angler from the Midwest primarily targeting Large/Smallmouth Bass.I decided on this model due to the size of my head (above average), the lens/mirror color (best for my freshwater/inclement cloud cover applications) and I opted for glass as Costa's 580 Glass is praised for it's clarity.I spent a lot of time trying to decide where to purchase the glasses as it's well known that there are many fakes/counterfeits out there. After looking at even well reviewed postings on eBay and other 3rd parties, I continued to come across images that had identifying numbers and small design differences from what was posted on Costa's website.When I saw the option to purchase them as shipped and sold by Amazon WITH the opportunity to 'Try Before you Buy', I committed.I received the glasses promptly and reviewed them to ensure they were the real deal and I could NOT be happier.I can't express how incredible they feel and the build quality and clarity of the lenses really is THAT good compared to every other pair I've owned. You would never know that the lenses are sitting over your eyes when wearing them - sooner that the world around you has simply changed to a copper tint.I've worn them already for several weeks and routinely can see further and deeper than any of my co-anglers.*Note* Anyone concerned about purchasing glass over polycarbonate for safety and weight reasons, this is my feedback:I regularly fish with heavy tungsten weights and have for over a decade. While I've been fortunate to never have a weight or hook come in contact with my glasses, I have had co-anglers that have. A close friend set a hook while punching heavy weed cover with a 2oz tungsten weight. The set was a miss and the weight hit directly in the center of his Maui Jim glass lenses (which are considered just as impact resistant as the Costa's)- while the glass DID break, it does NOT shatter. The glass is built with multiple different layers so that it spiders instead of shattering on impact. There were no sharp pieces of glass or shards that came out of the lenses. Additionally, for normal wear and tear, the glass will not scratch compared to the polycarbonate. After my 6 years with my Natives (while taking very good care of them) there were still many micro scratches in the poly lenses.As for weight: I feel no difference at all compared to the polycarbonate. If you research, Costa 580 glass lenses are nearly 30% lighter and thinner than nearly every competitor and I've not noticed any change. I feel 0 fatigue from wearing these glasses, even after 8-10 hours on the water.If you've been researching sunglasses and have this one on your list, I'd HIGHLY suggest these. I personally will be suggesting them to any angler that asks.Remember that your Lens/Mirror color may depend on your application and location. General guidelines:Grey lense/Blue mirror: Offshore/Clear Open water conditions with the brightest sunlightCopper lens/Green mirror: Freshwater applications where your light/cloud coverage varies.Yellow lenses: Low light - Dawn/Dusk - first+last hour of sunlight and for many sight fishing applicationsI hope this helps someone with their decision. They truly are amazing!