Adds preload and effective rate to rear torsion springs. Allows for more accurate ride height setup. Increases efficiency of rear torsion springs.This item fits the following vehicle applications:compatible with Ski-Doo Freeride E-TEC 800R 137 2014-2017compatible with Ski-Doo Freeride E-TEC 850 137 2018-2019compatible with Ski-Doo Grand Touring 550F Sport 2014compatible with Ski-Doo Grand Touring LE 4-TEC 1200 2014-2018compatible with Ski-Doo Grand Touring LE ACE 900 2014-2018compatible with Ski-Doo Grand Touring LE E-TEC 600 HO 2014-2018compatible with Ski-Doo Grand Touring Limited ACE 900 2019compatible with Ski-Doo Grand Touring Limited ACE 900 Turbo 2019compatible with Ski-Doo Grand Touring Limited E-TEC 600R 2019compatible with Ski-Doo Grand Touring SE 4-TEC 1200 2014-2018compatible with Ski-Doo Grand Touring SE ACE 900 2017-2018compatible with Ski-Doo GSX LE 4-TEC 1200 2014-2015compatible with Ski-Doo GSX LE ACE 900 2014-2015compatible with Ski-Doo GSX LE E-TEC 600 HO 2014-2015compatible with Ski-Doo GSX SE 4-TEC 1200 2014-2015compatible with Ski-Doo GSX SE E-TEC 600 HO 2014-2015compatible with Ski-Doo GSX SE E-TEC 800R 2014-2015compatible with Ski-Doo MX Z Blizzard 4-TEC 1200 2016-2018compatible with Ski-Doo MX Z Blizzard ACE 900 2016-2018compatible with Ski-Doo MX Z Blizzard E-TEC 600 HO 2016-2018compatible with Ski-Doo MX Z Blizzard E-TEC 600R 2019compatible with Ski-Doo MX Z Blizzard E-TEC 800R 2016-2017compatible with Ski-Doo MX Z Blizzard E-TEC 850 2018-2019compatible with Ski-Doo MX Z Sport 550F 2013compatible with Ski-Doo MX Z Sport 600 ACE 2013compatible with Ski-Doo MX Z Sport 600 Carb 2013compatible with Ski-Doo MX Z TNT 4-TEC 1200 2013-2018compatible with Ski-Doo MX Z TNT ACE 900 2014-2018compatible with Ski-Doo MX Z TNT E-TEC 600 HO 2013-2018compatible with Ski-Doo MX Z TNT E-TEC 600R 2019compatible with Ski-D