The PWR DRIVE CST screw is made of hardened steel to provide a degree of high tensile strength, high torque, and super shear strength that a regular lag screw just cannot offer. This gives an instant advantage of not having to pre-drill, which is quite a time saver on the job site. The sharp threads and points bite quickly, a type 17 tip reduces wood splitting and a clearing thread, called the "U" thread, reduces the friction on the screw shank, for reduced driving torque and more importantly increased battery life for your tools. The PWR DRIVE CST has a wide flat head with nibs and under-head cutting serrations for easy countersinks and will embed in wood with an incomparable clean finish. This screw also has a T-40 firm-grip drive provides exceptional torque strength and allows the CST to stick to the bit, which is paramount when working in tight spaces. The PWR DRIVE CST is part of the ICC/ESR-4558 evaluation, which certifies CST as fully compliant with the International Building Code (IBC) and the International Residential Code (IRC), for both its structural properties and corrosion resistance. This is why all CST have head markings for easy job site inspections.