The left arm cap on my Sayl snapped off at the end so I needed a replacement. These have done the trick. They are marginally shorter than the originals but are a similar width and height. They feel very similar to the originals in that they are a softish plastic. If someone had replaced them for me, I would never have known the difference from the original which is a good thing.To fit these is pretty simple. The arm caps are held on by a Torx T20 screw. You unscrew that, pop the original cap off, replace it with the new one then put the screw back in. Easy.