Slipknot is right on.My,up front fish finder is an eagle seacharter 500c.I paid 425.00 for this unit last year.It has G.P.S.It should be cheaper this year. I put the navionics chip in it.I found i liked it so much that i just use that one for way points and underwater topo mapping.I have a lowranceX107 in the back of the boat,the graphics are vastly superier to the eagle,same price range but no g.p.s.I must say again,that navionics upgrade made an unbelievable differance.I am glad i bought one that i could upgrade .Polebreaker