These are fixed bed brackets for the CR-10, Ender 3. They should replace the springs under the heating bed. Two firmware are required.
The new Ender 3 contains the spacers so you don't have to print the required parts. You only need to adjust the height of the limit switch module. If your printer is a CR-10 or Ender 3 old part, you need to print the required parts, reference files in thingiverse, keywords: CR-10 Solid Bed Mount.
The model is 3 high (18 mm) and 1 short (16 mm), black. (Print firmware not included). Please note: Before installation, you need to print two firmware (search for "3742788" in Thingiverse). An automatic level sensor is required. Please refer to the picture.
Ender 3 / CR10 needs to upgrade parts: replace original springs on your heated bed and no movement is possible, your set levels are retained.
4mm internal diameter makes it easy to level your 3D printer. New improved 3D printing levelling tool with two different colours to choose from.