It has a four sided square head at one end and a cup-shaped indentation at the other end

5/16-24 x 3 Grade 5 Hex Cap Screw Zinc Plated Domestic USA (100)

7 x 3 Simpson Trim-Head Wood Decking Screws - Square Drive 316 SS - Bulk Pail (1750)

7/8-14 x 2 Grade 5 Hex Cap Screw Plain Domestic USA (15)

0.188 x 4 1/2 Simpson Strong-Drive® SDWH Timber-Hex Screw 316 Stainless Steel - Box (100) 1 1/4-7 A307A Hex Bolts Zinc Plated It has a four sided0. 188 x 4 1 2 Simpson Strong Drive SDWH Timber Hex Screw 316 Stainless Steel Box (100) . Stainless steel structural fasteners designed for lag screw replacement. These 0. 188" and 0. 276" diameter hex head fasteners require no pre drilling, making them easier and faster to install than typical lag screws. Features: Type 316 stainless steel for maximum corrosion protection No pre drilling necessary in most applications Load values exceed those of