These are knobs for the Ender 3 to adjust the bed height that uses 4x M4 nylock nuts that are press fit into the bottom so the bed doesn't move on its own anymore. They have a similar feel and look to the stock ones

Required to use these 4x M4 nylock nuts

suggested to get also if you use a glass bed 4x M4 nuts 4x spring guides (STL included)

How to install them

1. Press the nylock nuts into the plastic using a vise, a clamp, or just hammer them in.

2. When installing these i also use 4x m4 nuts (nylock not required) above the springs to lock the bolts in place onto the heated bed, just don't over tighten them as you don't want to damage the bed.

3. After that i had to drill out the holes on the base plate (not the headed bed) to a size just a little larger since the bolts didn't want to line up when they were perfectly perpendicular.

4. Once the heated bed fits on again without any binding or forcing the bolts into the holes use the spring guides to keep them centered on the nuts touching the bed.

5. Put the springs on.

6. Put the new knobs on.

7. Adjust the Z stop and level the bed.