The EF184 is a purpose designed high gain frame grid pentode. The mutual conductance is 15.6 and the closely related (pin compatible) variable μ pentode EF183 has a μ of 12.5.

A frame-grid sharp cut-off pentode for use as an IF amplifier in television receivers. This implies a relatively wide band function at about 33 MHz. The high mutual conductance was important for wide band width amplifiers. 

The thin glass tube envelope is 20 mm in diameter and excluding B9A base pins, is 51 mm long. The electrode assembly is 13 mm top to bottom.