These are true vintage, ultra rare, May Optical USA eyeglass frames, circa  1960's, in excellent condition. These are New Old Stock frames that have never been worn or had lenses installed.  Frames are made of high quality acetate material in demi amber color showing nice hues of red in light.  Consider these frames super rare in 42mm size, which I've never seen or thought existed, let alone in NOS condition.  Frames are marked 42-24 on the right plastic nose pads.  Aside from a tiny manufacturer defect (machine nick & not visible when worn) on the inside right handle, picture 9, frames are free of any other nicks, chips or tear.  These frames just fit nice and are well balanced in design.  Frames look great free of scuffs and handling marks with May's signature joint round rivets on both frames and temples.  Hinges are firm with no movement or play.  Temples are straight and not spread apart.  Front face is in excellent condition.  Both edges and nose bridge look great free of scuffs.  Handles look good.  Inside rods are  free of green or corrosion.  Original screws in tact.  Frames retain a nice sheen all around with no discoloration.  May 20 marked on the inside left temple.  All other inscription is shown in photos. These are just fantastic frames not too many people know about.  Not too many going around.  And probably only one in 42-24 size.