HAset if for Aluminum crimps.
HDset is to DIN standard (DIN 46235 and DIN 46267).
HRset is to EN standard (international and European standards).
HLset this would just be a standard copper crimp die designed for the UK market, as there is technically no conformity needed for UK industrial crimps unless stated by the lug manufacturer (most people using SWA or Klauke L series lugs would use this).
This is applicable for all series of dies, such as 4 Series, 13 Series, 15 Series and 22 Series dies. For example HA4SET, HA22SET etc.