I'm ready to update the software on my Helix 9 Gen3 DI and Helix 9 Gen3 DI units and need to know what size card do I need. Some of the info I've read talks about formatting the chip. I don't have a clue as how to do that. Can I use the same card with the new software update in both units without having to buy another card ? Also I have a Garmin Echomap Plus 93 sv unit that I need to update too. the same questions apply to the Garmin.