The STIHL FG 4 Roller Filing Guide is a simple and easy-to-use accessory that provides a smooth filing action while holding filing angles. This helpful tool sharpens saw chains with ease and accuracy, while checking and assisting with lowering depth gauges. Featuring a patented STIHL design, four roller guides and an integral fold-out filing plate, the STIHL FG 4 Roller Filing Guide brings you the engineering expertise of STIHL, so your chain will be ready to perform.