I didn't know this subject was already covered in the post called “ Nothing To Do With Anything-
Totally unrelated to Harbour Lights or Lighthouses"

I just found it over there today.

Reading over what Dave Said I will agree that the number is HB-905 because Tony said it is and a HL-905 doesn’t fit in and wouldn’t be accepted by other dealers. But I recall it being accepted as a HL by the forum and I even called Lighthouse Depot at the time and the girl there quoted me a HL-905.
Halfway Rockon the Forum listed as HL-905

Halfway Rock on the Forum as HL-905 and CLH-101


But again if Tony says it is a HB-905 that is the number we should go by.