Thread Size: 1/2-13; Screw Length: 4.5"; Package Contents: 4 pieces Diameter of the head: 1.09" (27.79mm,max); Height of the round head: 0.27" (6.86mm,max); Height of the Neck: 0.28" (7.14mm,max) Material: Crafted from high-grade 304 stainless steel (18-8) for exceptional strength and corrosion resistance—naturally durable without coatings. Outlasts regular steel and zinc-plated fasteners in harsh environments like moisture, chemicals, or extreme temperatures Design feature: Big round domed head designed to eliminate the need for a washer; Square neck underneath the head helps self locking; Their strong holding power ensures the stability and reliability of your contructions; Use wrench or plier tools to turn the square neck to install them Ideal for demanding outdoor/industrial applications—from agricultural machinery and bridge decking to marine fixtures—these carriage bolts deliver permanent anti-rotation security and zero-maintenance integrity in corrosive environments Carriage bolts are desgined with a big smooth round domed head and a square neck underneath the head. The big head helps eliminate the need for a washer and the square neck is self locking to eliminate spinning and the need for a driving tool. Carriage bolts are commonly used to fasten a wooden part to either wood or metal frame. The 304 stainless steel provide perfect strength and good corrosion resistance in bad environments like high temperature, cold weather and high humidity areas without the need for time consuming and costly maintenance.