5mm Radiator key

Fredxxx · 2014-05-13T17:12:08+00:00

I have a radiator, I believe of the Stelrad type with the round top. It had a square key on the back that is very tight and is difficult to get to. I have a key that fitted, but was of the die-cast variety and is now broken though a combination of force require and it being weak. I have measured what's left of this key and the internal measurements are a nominal 5.2mm square. The standard key I can get is way too large, presumably 1/4". An ideas where can I get a *strong* key that will fit?