The Grey Pneumatic 3542S is a 3/4-inch drive by 1-5/16-inch fractional standard-length impact socket featuring an 8-point (octagon/double square) opening. It is engineered primarily for heavy-duty industrial and railroad applications where square fasteners or plugs need to be driven with an impact wrench. Key Specifications Drive Size: 3/4"Socket Size: 1-5/16"Output Type: 8-Point Octagon / Double Square Length: Standard length (approx. 2.20" to 2.44") Material: High-strength Chrome-Molybdenum alloy steel (Cr-Mo) Drive End Diameter: 2.50"Hex / Bolt Depth: 1.18" to 2.36"