... 25.4 , 28 , 31.8 , 33, 35, 36, 38.1 , 40 , 41.8 , 42 , 45, 48 , 50 , 50.8 , 56 , 57 ... , 108 , 114 , 127 , 133 , 141 , 159 , 168, 219 b) Square tube side length , mm : 10*10 , 12*12 , 15 ... , 36*23 , 36*36 , 38*25 , 38*38 , 40*10 , 40*20 , 40*40 , 45*75 , 48*23 , 48*48 , 50*25 ... 13*33, 20*30, 15*38, 15*42, 20*40,13*44, 25*38, 28*42, 25*49, 28 ... 10*33, 15*35, 18*33, 23*31, 15*41, 17*45, 33.6*24, 19*38, 25*35 ...