... , Hardened Couplers are Adopted, Heavy Duty Steel Props Steel props (light duty) I: 1,920-3,500mm, 26. ... 520-3,900mm, 28.66lbs2,920-4,500mm, 32.19lbsSteel props (light duty) II: 1,920-3,500mm, 27. ... 200-3,900mm, 66.14lbs2,700-4,900mm, 77.16lbsSteel props (heavy duty) II: 3,251-4,877mm, 59. ... , 46.30lbs1,803-2,997mm, 40.34lbsHigh quality steel usedHardened couplers are adoptedLoad test passed steel props