Specifications Screen size:3.9' Depth Range0.7-100m Battery Life5h Wirelss Operational Range500m Sonar Frequency/Beam Angle45 degree in 200khz(wireless) Operational Temperature-10-50 degree Application Scopecarp fishing Peculiarity fish finder FF918C-WL. Professional and amateur fishermen love this fish finder to find out the location as well as the depth of fish and bottom contour of water. Ideal for Ocean, river or lake and detecting a Fish or school of fish in any particular area has never been this easy. This fish finder literally brings the fish to you. This fish finder is designed to be used with a bait boat. Just simply install the Long - Distance signal tower (transmitting antenna) to your bait boat, power on the signal tower, then you can power on your fish finder and enjoy fishing.