one more thing that i forgot to mention.some people beleive that you dont need traditional 2d sonar. i really dont understand this but hay everybodys got there own opinion. really its the ones that say there sonar experts that i dont understand saying that but anyways the 570 di has a 455 khz 16 degree traditional 2d sonar thats really the only down view thats truely under the boat that i no of in this class of unit.just because di shows a fish on it doesnt mean that is beneath the boat.it could be to either side,no way of noing. at 100 ft. you have 150 ft of coverage with di