Stewart Warner Tachometer. 551AHK-D.
The Stewart Warner 551AHK-D is a heavy-duty tachometer with a black face, white numbers, and a 0-3,500 RPM range. It has a gauge diameter of 86 mm, a .5 to 1 cable signal input, and a black bezel with a silver ring. It is 3 3/8 inches in diameter and has a voltage of 12 V (light).