This is the .JJC Lens Hood Standard 72mm [JU1172] This is a universal, bayonet fit lens hood designed to screw into the filter thread of a single lens reflex (SLR) camera lens. The lens hood is supplied as 3 parts Lens mounting ring which screws into the filter thread of the lens. Locking ring which screws onto the mounting ring to lock the part onto the lens. Lens Hood which bayonet fits onto the mounting ring. The lens hood may be reversed mounted depending on the lens in use. Assembly instructions Screw the locking ring onto the mounting ring until around 3mm of thread show through the locking ring. Screw the mounting ring onto the filter thread of the lens. Unscrew the locking ring until it touches the filter ring and locks the assembly into position. Mount the lens hood onto the bayonet fitting of the mounting ring and twist a ¼ turn clockwise to lock into position. Twist anti-clockwise to remove the hood. Note: Twisting the lens hood into the locked position will be stiff on a new unit. This is normal and will ease with use. ...Contact us if you need more help.