A lamp base (10), for example, for a tungsten-halogen lamp, comprises three electrically conductive parts or elements and a glass insulator. Specifically, the lamp base (10) comprises a first metallic outer part (12), a glass inner part (14), an electrically conducting eyelet (18), and an upper electrically conductive part (20), all symmetrically arrayed about a longitudinal axis (16). The glass insulator (14) bonds all of the electrically conductive parts, (12, 18) and (20). The metallic outer part (12) is preferably threaded for insertion into a socket and has a major, internal diameter D1. The glass inner part (14) has a primary, external diameter that is equal to the major internal diameter D1; i.e., the external diameter of the glass inner part (14) is contiguous with the internal diameter of the metallic outer part (12). Further, the internal glass part (14) has an opening (14a) therein and the opening (14a) has a secondary diameter D2In an aspect of the invention, D2/D1 is greater than 0.5 and less than 0.6 and, in the preferred embodiment of the invention, the ratio D2/D1 is 0.58.