Coarse Style: Thread Kreg Screws are available in two thread types—coarse and fine —to match the screw-holding abilities of different types of woods. Both thread types feature a self-tapping tip that 'drills' its own hole, so the screw drives in quickly and easily without splitting the wood—and without requiring a pilot hole in the mating workpiece.Coarse-thread screws are recommended for use with softwoods—as well as for sheet goods such as plywood and MDF—that are soft and not very dense. Coarse screws have deep, aggressive threads that bite into those soft fibers to ensure solid holding power.Head Style: Maxi-Loc Ordinary woodworking screws and drywall screws have a head with a conical shape on the underside. The head on a Kreg Screw is perfectly flat on the underside to mates perfectly with the flat bottom in a Kreg pocket hole. When you drive a Kreg Screw into the pocket hole, this flat shape applies force straight toward the screw tip, so it holds the joint tightly together without deforming the pocket, which could split the wood. Kreg Screws are available in two head styles.Maxi-Loc screws are the Kreg Screw of choice for the majority of applications. These Kreg Screws have a large head that provides maximum bearing surface as the screw pulls tight in the pocket.Screw Length: 1 1/4" Selecting the correct screw length is the most important consideration when choosing a Kreg Screw. To help select the right screw length when joining materials of different thicknesses, our Screw Selector Wheel is a handy tool.The threads on a Kreg Screw stop partway up the screw shank, which leaves a smooth area below the screw head. When the screw is driven in, the threaded portion grabs into the workpiece you’re attaching to, pulling the screw in. The other piece glides freely over the unthreaded part of the screw, allowing that piece to pull tightly against the mating piece—without unnecessary threads that can actually push the joint apart.