Genuine BMW control light safety belt. Located in the interior glove box light/lamp that was used across several classic BMW models.
On the BMW 2002 (E10), this rectangular lamp is typically located inside the glove box compartment.  Location: It is generally mounted at the top or side of the glove box interior casing. 
On the E9 (2800CS, 3.0CS/CSi/CSL), this part is also used primarily as the glove box illumination. Location: It is integrated into the upper portion of the glove box assembly, often hidden from direct view until the lid is opened.