The 4-step gray scale provides extra clear images of the soil, fish and the structure under water.  The fish finder has a depth range of 36.6 meters.  This fish finder is equipped with lights, so you also at night have a clear picture of the soil and fish.  With 1 button lets you navigate through the entire menu.  The temperature of the water on the fish finder also shown.  The RF 15 works on 8 AA batteries.  As an option, we offer you a battery pack that allows you to the RF 15, 50 hours of use.  This saves batteries, and is better for the environment!  Characteristics:  Range up to 300 meters, tested to 350 meters  A and B channel  Conservation sonar 90 degrees angle for optimal registration  Simple assembly and disassembly  Waterproof  The model 2008 is implemented with a new antenna in which any state can be bent, so it is suitable for any vehicle boat. The results are much better, allowing any fish finder has been tested to 350 meters.  Display:  Diagonal screen size 9.8 cm  Display Resolution: 160 x 132 V H  Display type: LCD FSTN  Display number of colors: 4 shades of gray  Sonar: 125 Khz