These are the laser-cut V2.4 kinematic bed mounts, meant to limit the effects of heat on your aluminum build plates, otherwise known as the taco effect.
Comes with all the fasteners you need to get this up and going. Please note, it does not work with the FYSETC kits as they do not follow the spec 150mm spacing requires to use this.
Please note: this raises the bed height approx 8mm, you may need a longer pin for your Z end stop (e.g. 35mm pin vs 30mm).
For additional information as well as installation instructions see here.