Dimension measuring device

To measure the gaps between fuel rods in a fuel assembly, a feeler gauge is provided with a pair of resilient arms having elongated electrical resistance strips carried by their confronting surfaces and extending from terminations adjacent the free ends of the arms through a contact point of electrical inter-engagement. The strip terminations are wired into a metering circuit including a current source and an ammeter. When the arm free ends are positioned in a rod gap, the position of the contact point relative to the strip terminations determines the magnitude of resistance included in the metering circuit, and the meter registers the gap dimension.