Too be honest I am not sure, I have seen both numbers floating around. I copied that from one of Rogers posts. The interzoo flyer says 6125, found earlier posts saying 6135 which is what I posted on our site, which guess I might have done wrong. Thinking there was a model name change maybe to 6125 as output is 12000lph thus the 612x numbering... or maybe was just a typo in the beginning.