i think the lowrance h20 goes for 160 has a base map of the united states and shore lines and major highways. buy a lakemaster chip and your set, but the chips are area specific but then will show the local roads. it is also easy to use. check out the websites lowrance, garmin, lakemaster pro maps, navionics. looks at the specs. and base your decision on that. ps. the map chip is going to run like 100 at for lakemaster i am not sure about navionics, i do know the area i wanted navionics was more money and not as accurate. just my .02, all i can say is read read and read some more. if you know someone that has one borrow it and see how you like it.