It is a QUAD LOCK concept, it was designed to be compatible with the original, I have verified it.
The thickness of the gasket around the bar is 2mm. So, you can cut a simple piece of rubber gasket with 2mm thickness or, if you use a TPU like a rubber, you can print it.
WARNING: I used Inserts in all parts of Quad Lock Concept.
Parti List
1) 2mm dia x14mm long Steel Pin (qty 1)
2) M4x8.1 Ruthex Threaded Insert (qty 1)
3) M5x9.5 Ruthex Threaded Insert (qty 1)
4) M4x16 Hexagon Socket Cap Bolt
5) 2mm gasket (or print your self using soft TPU)