. "Preferably, the cross-sectional dimension Z of the knuckle portion 61 is in the range between and including about 1.6 to 3.3 times greater than the cross-section dimension F of the finger portion 65, with typical dimensions comprising the ratios of 2.5 mm to 1.5 mm (1.6 times) and 2.5 mm to 0.75 mm (3.3 times)." . . .