This is the "improved" version of the HA which was advertised as the first direct drive chainsaw. This model is what is usually found or will come across as the HA was quickly upgraded to the HB. It is a stout little saw that has a nice sound with the cast muffler. (still has the cool swivel handle for bucking or felling). Added bonus with the HA or HB is that if the saw has compression and spark the float carburetors are pretty straight forward to clean and get going.