38pc 3/8" 1/2" Duo Combo Impact Socket Set Deep & Shallow Metric SAE Flank Drive 38 Piece 3/8" & 1/2" Flank-Drive Combination Chrome Vanadium Steel Impact Socket Chrome Vandaium Steel; Drop Forged; Heat Treated Thin Wall Design Allow Sockets to Fit Into Tight Places Sockets made by the cold extrusion process which produces a Stronger and more Durable socket. Special Chrome Vanadium Steel and Nice heat Treated