Magnetic tape measure square tool

Need to measure a square or rectangle for squareness, but can't find someone to hold the tape measure for you? problem solved. takes a single 608 bearing. press in the top, press button in. center edge of tape is placed directly where the corner you'd measure from with arrow pointing direction to measure. clearance for weld on outside of square so cleanup of tack welds is not necessary. requires 4 ) .5"x .125" magnets.