The Skylight filter for 52mm thread lens has a slight straw colour to help reduce blue hue when taking photos in open shade overcast days and snow. It's also used to protect the lens. This one is badly worn coating (see condition note) so buy to create special effect filter painting suface of glass with nail varnish for spot effect or diffuser. Or for the vintage Asahi Pentax rim which is in good condition
no scratches but coating is blotchy so sold as seen.