Heater plug, to fit tractor models;

Fordson Dexta, Super Dexta, 

Ferguson TEF20, Ferguson FE35,

Massey Ferguson 35, (4 cylinder).

1/2" BSP thread.  

please note; there are 2 different lengths, 

these are 87mm total length, 60mm long from underside of hexagonal head to end of coil.