This little gadget (from the early 1960s? - It has the EF183 and EF184) gives the pin functions for many Mullard valves. One side has 7 and 8 pin valves including many older octal ones - ECC33-4-5, EL34, GZ34 etc. The other side has all the commoner Noval ones including ECC83, EL84 etc. You slide the green cursor until the valve type appears in the bottom window, then the pin functions are visible in the other windows.