USB voltmeter and ammeter RD UM34/UM34C with a digital display and compact dimensions of 71.2 × 31.8 × 12.4 mm (2.80 × 1.25 × 0.49 in). It operates on DC power, is FCC- and CE-certified, and is intended for electrical DIY and monitoring; rated to work between about 14 °F and 212 °F.