If you check inside (the portion that is towards the face) of the bridge , @ the center , you should find two numbers , the smaller one = bridge width , larger one = lens size (in millimeters) , in the event you want to go looking for replacements .
These look to be 1970's era to me , usually purchased by sportsmen , aviators , cool dudes & etc ... most common tint was amber "anti-glare" , although they also were available for use with prescription lenses & various custom tintings .
Thin & rather light-duty temples were a bit of a faulty design , considering that all lenses 'factory-mounted' by B&L were made from glass & could have been made with a little more 'beef' to them , but these frames (often called 'aviator-style') were the fashion statement that alot o' ole boy liked .
Many (most) people produce acids that eventually eat through the surface gold & expose the base metals underneath , in frames made as these were .
Finding an intact & original set of eyeglass frames sans such wear/damage is much more in line with an eyeglass collector would be looking for (original & unused) IMO .