The X41 is a triode hexode frequency changer designed for AC mains receivers. The X31 was designed with a heater for universal mains (AC/DC sets) but is otherwise identical.
The X41 was made with a plain bulb as here or with external metallic screening paint.
The Osram paper brand label.
The wire seen on the left is the connection between the cathode pin and any external metallisation.
The classic envelope is 44 mm in diameter and, excluding the B7 base pins, is 117 mm tall.
References: Data-sheet & 1043. Type X41 was first introduced in 1935. See also1935 adverts.