Our high quality, "Style A" 2 ½" hollow drill bits come in select sizes to create holes with either 1/4" or 5/16" diameter. They are compatible with the Spinnit® FMMH 3.1 hydraulic paper drill and come either uncoated (standard) or coated (Teflon). The standard bits are meant for low volume usage, but the Teflon coated bits have a lubricated, low-friction, corrosion-resistant surface that makes it perfect for medium and high volume usage. If you are ready top replace old and worn out bits, or if you want to offer more versatility with a different hole size for your FMMH 3.1 drilling machine, then buy the 2 ½" Style A hollow drill bits online. To keep your drill bit performing at it's peek, be sure to sharpen it for every one to four hours of use using an sharpening tool, such as the MS-1 precision drill bit sharpener.