Plug part (1) for establishing an optical and/or electrical plug-in connection (2) with a mating plug part (3) by plugging together the plug part (1) with the mating plug part (3) in at least one plugging-together direction (4), the plug part (1) having a plug part housing (5) and at least one optical and/or electrical contact (6) and an elastic opening prestressing element (7), acting in a direction parallel to the plugging-together direction (4), and an opening element (8) for opening a flap (9) on the mating plug part (3), the opening element (8) being mounted displaceably in relation to the plug part housing (5) in directions parallel to the plugging-together direction (4) in or on the plug part housing (5), and being prestressed in one of these directions parallel to the plugging-together direction (4) by the opening prestressing element (7), wherein the opening element (8) is formed as a one-piece body and has a first abutting face (10) for the opening prestressing element (7) and a second abutting face (11) for the opening of the flap (9) of the mating plug part (3).