Vktech Digital DC Ammeter 20A Red LED Panel Amp Meter Digital Electricity Meter Power supply: DC 4.5--30V. RED: + BLACK: - Test current: 0--20 A. RED: + BLACK: - Mounting cutout: 45.5 x 26.5mm (L*W) Dimension: Approx.48 x 29 x 21mm(L*W*H) Color:As shown