IKEA MARKUS armlest adjuster

This is a part to raise the height of the armrest. With this, the height of the armrest can be increased by about 21 mm. It can be used in either the front or rear screw holes for attaching the armrests.

If you want to change the raising height, I have published the data of fusion360, so please adjust it yourself.

https://a360.co/30aRAen