everytime i have gone ive gotten 20% off everything except non HD items like WD40 or Drag stuff they carried. I got everything from a hat to a leather jacket and from oil to a razor tourpak and stage 2 kit. They honor everything that has a HD stamp on it.
I see Williams HD is having a 30% off discount on licensed products tomorrow from 9:00am to 12:00pm. From the advertisement, I do not believe this applies to HD branded parts and accessories.
I will tell you that last Saturday (11/17/2018), I did get 30% off all the HD parts and accessories (in stock) that I purchased at Tramontin HD. I picked up all sorts of maintenance items.