McMaster 91257A640 Zinc Yellow Chromate Plated Hex Head Screw, Grade 8 Steel, 3 8" 16 Thread, 4" Long, Partially Threaded, Pack of 10 EC 3101 Fractional Tap Capacity 1 16 in Fractional Tap Capacity 1 16 in to 1 4 in Socket Point Styles Included 6 Features Side Locking Hole Impact Rated Yes Material Alloy Steel Insulated No Number of Standard Sockets 21 Piece Count Range 2 to 25 Compatible Fastener Type Bolts Non Sparking No Socket Shape 6 Point Includes Deep Sockets No Container Type None Locking Yes Non Magnetic No Tether Ready No Includes Standard Sockets Yes Includes Drive Tools No 000 psi Hardness Rockwell C33 Minimum Thread Length 1" Performance High Strength Screw Size Decimal Equivalent 0 These have a head with six flat sides to keep wrenches and sockets from slipping and rounding off the drive