The 30L15 is a low impedance high gain double triode. The low voltage high current suggests a low noise design. The 30L15 was designed for cascode RF amplifier use in the front end stage of VHF television tuners.
Both triodes are surrounded by a screen and also separated by a centre screen.
The thin glass tube envelope is 20 mm in diameter and, excluding the B9A base pins, is 48 mm tall.
References: Data-sheet & 1040. Type 30L15 was first introduced in 1960. See also 1960 adverts.