Blue Sea 8110 Mini Clamp-On Hand Held Multimeter

The spring loaded jaws of the clamp allow measurement of current without interrupting the circuit. For example you could measure the output of an alternator by clamping on its output wire or measure the power consumption of a winch or windlass by clamping on its power cable. You can only clamp on a single cable, if you clamp on a pair of positive and negative wires the readings of one cancel out the other.  When comparing this to other meters note that this clamp works for AC and DC but not all meters do.  This meter reads RMS voltage which is a feature not found in cheaper meters so it will give a more accurate reading of voltage when reading irregular wave forms, for instance those produced by some inverters.