Been using these for about four years.  They are perfect.  In the sun I use the blue tinted ones.  The material is flexible and seals to my face well.  They seem to last for about 1.5 year of swimming 3X a week for about an hour.  They can get a little foggy and start to turn black in the lens seams. I could probably do a deep cleaning, but I usually buy a new pair.  This is common with many goggles.