e165 charts compatibility and ordering

[Lazybones]

There seems to be some confusion on chart compatibility with the e165.

The west marine technician said that we must choose which e165 bundle? to decide on which charts, c-map, Navionics, Noaa, will work with the e165.

I see that the model E70025 has dual micro sd cards. Can we use either navionics or c-map as we see fit, or must we select one or the other only that we must use for the lifetime of the product?

If we can use what we want, when we want, assuming we have the right chip, can both chips be used at the same time, allowing to switch back and forth between chart types?