Attract fish to your downrigger wire with the most advanced Black Box on the market. New advanced chip technology allows total voltage control at a budget price. LCD readout shows your voltage, which is adjustable from .001 to 1.0 volt. One Black Box can control up to six downriggers. Includes two wire harnesses and two downrigger contact sleeves. Can be switched from imposed voltage to natural voltage for checking circuits and boat condition. Includes complete instructions and two downrigger contact sleeves. Per 2. Available: Black Box System.