Ideal bullhorns for an 0 gauge Heljan ETH class 37/4. These are carried by 37403, 405, 406, 411, 412, 415, 416, 419, 420, 424, 427, 428, 429 & 431 at various times. Lately they have been removed by EWS and DRS. 
These are stainless steel primed in etch white primer because the yellow on Heljan locos does have variations in the shades. These are handed with the raised line to the outside of the loco. Fitting is by drilling a 0.5mm diameter hole all the way through the body and a spot of superglue on the leg.