After 3 seasons with a Lakemaster in my Lowrance 520C's, I would lke to find a card that offers different colors as the depths change. Right now I see lines and numbers but the color is all the same. I have to take glasses off and git reel close….Are these new 3d cards useable in my 520's?? Or is there a 'magnifier' that would cover the whole screen? Thanks for the help. [smilie=applause.gif]