Both the QTR-8A and QTR-8RC have the same physical characteristics. Each array measures 2.95" long by 0.50" wide and has a maximum thickness of approximately 0.125". Without header pins, the unit weighs 0.11 oz (3.1 g). The individual reflectance sensors are distributed evenly on the board at 0.375" intervals. The mounting holes are intended for #2 screws.