Ive done a few web searches before posting this, but havent come up with much accept for varying software versions. Ive noticed theres still a # of a GB's for sale with MAP of 499(5" coil). The pro model MAP is more. The spec sheets on fisher labs site appear to read identical.... What are the differences? Is one version better than another for say shallow water/relics? Or is there more to it than just software versions. ps, Im not opposed to PM's