Flexible, comfortable

These are made of a kind of soft vinyl plastic which molds well to the face.  Mine had a little bend in it from shipping which soon corrected itself with a little wear.  I can wear these over my glasses.  It does not make a perfect seal like a scuba mask, but on me it's sealed everywhere except the very corners where there is a few mm gap.  I don't think these are made for sealing perfectly, but for protecting the eyes from splashes etc and they are brilliant for that.  The front 'glass' piece is so clear and easy to see through I would recommend these on that factor alone.  It comes with a protective strip on the front to keep the viewing area scratch free when it arrives.  These are not super high-end aerospace stuff-- it's simply a good pair of semi-flexible goggles for preventing splashes that you can comfortably wear over your prescription glasses.