STIHL RMA 510 V 21 in. 36 V Battery Self Propelled Lawn Mower Tool Only Direct to Stud Shower 3 13 16 Certifications and Listings UL The rustproof injection molded 3 13 16 Certifications and Listings UL Listed Manufacturer Warranty 1 year limited warranty 400 strokes per minute (SPM) for smooth The mower’s self propel function features a variable speed setting control 36 V Battery Self Propelled Feature 10 Text Feature 1 Text Self propelled with variable speed drive a squee Feature 2 Text Brushless electric motor with ECO mode the motor Feature 3 Text Zero or low exhaust emissions Feature 4 Text Mower can be stowed in three positions: folded or Feature 5 Text Locking key key prevents accidental starting of Feature 6 Text No gradual drop in power