Stihl FS 91 R Professional Trimmer, 28.4cc EngineStihl FS 91 R Professional Trimmer, 28. 4cc Engine Demanding landscapers can save time using the STIHL FS 91 R professional trimmer. With its larger fuel tank than the FS 90 R, this model provides 30% longer run times, as well as a three step start procedure to get to work faster. Thanks to its superior air filtration and low emission engine, the FS 91 R is a dependable tool with great maneuverability and power. Its rubberized loop handle is designed