This is the plastic, bayonet-mounting lens hood which was originally supplied with Pentax's SMCP-DA 17-70mm f/4 AL (IF) lens, and is offered here as a replacement for a lost or damaged hood.
This hood bayonets upon the tabs found on the outer diameter of the lens barrel, and is designed to provide perfect shading with a 17mm lens upon a APS-C style (15x22mm format) camera. It is not designed for any other lens.
Exclusively intended for the SMCP-DA 17-70mm f/4 AL (IF) lens