chip for lowrance 520c

my dad has a lowrance 520c. he is looking to buy a chip for an upcoming trip to minnesota. not sure which 1 to buy. any ideas guys?

I had a 100k US topo for my 520c and didn't care for it. Instead, I downloaded from Lowrance their free lake maps. I don't recall if they had Minn in their database but the ones I got for Okla and the surrounding area are very good. It's been awhile since I did it but here is their web site.
Enhanced Lake Maps