Eliminate the guesswork from inside measurements with our latest OneTIME Tool, the Modular Bar Gauge System. Inside measurements with flexible tape measures and fixed-length rules both present challenges. Everyone has tried to read a curled-up tape in the corner of an assembly. Ancient builders solved the problem even before graduated rules were invented. They used sliding bar gauges to create an exact physical reference for an inside dimension. Our modern version of this timeless design delivers a very versatile bar gauge you can adapt to dozens of tricky measuring jobs in your shop.