Comparison : Item # 100C450BRM7, 1-8 X 4 1/2 HEAVY HEX ROT MILL BOLT A193-B7
Item # 100C550BRM7, 1-8 X 5 1/2 HEAVY HEX ROT MILL BOLT A193-B7
Item # 125U350BRM7, 1 1/4-8 X 3 1/2 HEAVY HEX ROT MILL BOLT A193-B7
Item # 125U450BRM7, 1 1/4-8 X 4 1/2 HEAVY HEX ROT MILL BOLT A193-B7
Item # 125U550BRM7, 1 1/4-8 X 5 1/2 HEAVY HEX ROT MILL BOLT A193-B7