A bolster for use in construction having a plurality of leg members arranged in generally parallel spaced relationship to each other, a beam integrally formed with the plurality of leg members and extending transversely across the leg members, a first plate affixed to one side of the plurality of leg members and a second plate affixed to an opposite side of the plurality of leg members. 5 \u03bcm and about 500 \u03bcm, and said pillars have diameters in the range from about 20 nm to about 5 \u03bcm and aspect ratios of from about 2 to about 50, and methods of making and using them. In the calibration mode, a known load current is passed through the conductor, the microcontroller selects the trip level that is related to the load current, determines the load current from the current signal, and sequentially calibrates each of the plurality of trip levels for the respective known load currents.