The used HB-64 Bayonet Lens Hood from Nikon is a petal-shaped lens hood for the Nikon 28mm f/1.8G AF-S lens.
A lens hood serves primarily to deflect stray light and flares from reaching the lens when shooting toward your light source. It also serves to protect your lens from accidental impact and bumps. This lens hood is made of hard, black plastic and snaps into place on the lens or on a 67mm lens filter.