This is a belt clip for the 2" push dagger found on Aliexpress for $3. It allows you to carry the knife inside your waistband. The clip slides under the belt loop of your pants so that the sheath is securely attached. Note: 2" is distance from the tip of the blade to the rubber part of the handle. The actual sharp part knife is like an 1.2"

To attach the clip to your knife you will need two 2x12mm bolts and nuts.

If you have the larger 2.5" knife, I made a larger belt clip for that one too: https://www.thingiverse.com/thing:6879576