I just returned from Franks and I did upgrade my Lowrance from 4.0 to 4.1 before I left. It downloaded fine but there was a glitch. Now that Lakemaster was sold and does not support the Lowrance products, the upgrade does not show some items on the gps. Namely all the BOUYS on LOTW. I called them when returning home and they confirmed what I found. They are sending me a copy of 4.0 to reinstall on my HDS, no download is available, and that will fix things. My other option is to use Navionics products instead of the Lakemaster. If only I could remember where all the bouys are and which side to travel on.