This is a Tamron Rear Lens Cap for Pentax AF mount lenses. Rear lens caps are easy to lose while shooting on location, so it's well worth investing in a spare.
JJC Rear Lens and Body Cap Combo L-Mount
Tamron HB011 Lens Hood for HB011
Fujifilm 52mm Front Lens Cap II
Sigma 52mm Lens Cap
Nikon LC-K101 Front Lens Cap for 19mm f4E ED
Sony ALC-F863 Front Lens Cap
