Well, design-wise, they are absolutely identical. But look at the second image, which is the Propstore “stunt” flamer . It had the “4-HK” version (with hyphen), and I know of at least one “hero” flamer with the “4-HK” coupling as well.


The 4HK looks to have a narrower flange band at the base ...

This is featured on the DVD extras for the Quadrillogy box set.