Pilot drills are necessary before a screw is being inserted or when a hole saw is in use. Creating a pilot hole will prevent your wood from being split when screwing into it. These pilot drills can also be used as an arbor with a hole saw. This can be a great measure to eliminate any problems for your project.
The importance of drilling a good pilot hole is one that is wide enough to fit the shank of the screw in, but smaller enough to allow the screw to grip the material. At RS we have a large range of pilot drills to suit your needs from Starrett and our own brand RS PRO.