These sounders are for hard-core anglers. Both models come in power output ratings of 1kW, 3kW or 5kW, plus dual-frequency operation in any combination of 28kHz, 50kHz, 75kHz or 200kHz. Entire Image Control lets you vary the gain and STC of the whole image, including previously captured ones. When the sounder picks up clutter, say in the first 20 feet, you don't have to adjust the gain for the entire range and lose weak targets at great depths. The feature also lets you analyze ground and schools of fish you've already covered. Each model has a 16-color display and nine background colors. The CVS-842 has a 10.4-inch diagonal TFT LCD screen; the CVS-852 has a 15-inch diagonal TFT LCD. All the frequency and power outputs are built in. Depths range from zero to 8,000 feet. Price: $4,999 (CVS-842), $6,999 (CVS-852). Koden, (727) 576-5995; www.si-tex.com.