Original PHILIPS MINIWATT E448 = RENS 1224 used tube
from 1930's
HEXODE Frequency converter
Vf 4 Volts / If 1 Ampere
X4122 = E448 = H425N = MH4100 = TE48 = QV4100 = NSS45
I think the tube is not used, looks great, 200% emission:
Ia = 6mA
where 100% for the new tube is 3mA
the tube has Europe 7-Pin (C7A) base, top contact
you will get the tube you can see at the pictures
I always send the tubes by priority registered mail with tracking number within hours after receiving payment