Change the stroke on the Ohlins TTX Air m.1 rear shock by unthreading the end-eye and sliding these spacers onto the shaft to get the correct stroke. All TTX Air shocks arrive from the factory set up in the longest stroke.Intended for the m.1 version of the TTX AirKit includes (4) stroke reducing spacers and (1) stroke/volume reducerSpacer one (7mm long = Full stroke), Spacer two (9.5mm long = Reduces stroke 2.5mm, Spacer three (12mm long = Reduces stroke 5mm, Spacer 4 (14.5mm long = Reduces stroke 7.5mmThe 7.5mm stroke/volume reducer is larger with a different appearance due to it serving as both an air volume reducer as well as the stroke reducer Ohlins Rear Shock Stroke Spacer Rear Shock Tune Kits UPC: 840153640513