Used Vintage Front Lens Cap
SN 223/18-40.5Φ
2103036
Not sure what brand it is. It says that it is 50.5mm inner diameter. So it should fit lenses with 39mm filter rim. Or maybe 40mm? Not sure. It is slip over type cap. It will not fit lenses with 40.5mm filter rim.
Item has been used with signs of cosmetic use - it may have some scratching from normal use. But it is not damaged in any way, no cracks (see pics). This lens cap is fully operational and functions as intended. I would rate it a 7, on a scale from 1 to 10.