Viscount - Millard - Franklin - Other makes
This turn knob lock is suited to older style, pushout windows, it has a Knob Lock With Metal Plate, Black.
They pop rivet onto window. Plastic is held to metal with a rivet.
They are used in replace of the old style Caravan part in many different types of Caravans, Campers.
Please check pictures and item to make sure they are the same type as yours.
Made from solid durable plastic and steel.