The Sonic/Ergo/43a aerobar is a great option for any rider looking for a neutral wrist angle and positioning versatility The 43a is an enhanced version of the popular t3 extension The Sonic/Ergo platform offers a large range of adjustment in every dimension ÔÇô enabling riders to optimise the comfort of their position Fit range: Armrest Offset -70mm to -17.5mm in 7.5mm steps, Armrest Width 124mm to 290mm in 18.5mm steps, Armrest Stack 60mm, Extension Width 100mm