Folks

Don't worry about this. Just don't buy from them.  If you need single vision lenses, try Zenni Optical. (Google it)

Their glasses start at $6.95/pair INCLUDING single vision lenses.  I get 'aviator' style titanium frames with photo chromatic lenses, UV and anti scratch coatings and they cost about $45 per pair. 

I caught a buy 2 get one free sale and for $210 my wife and I EACH got three pairs of glasses.  They have a good selection and a feature where you can upload your photo to see what you will look like with various frames.