I'm trying to identify the pictured fastener. It's a single piece around the arm of a gas spring, allowing it to pivot. I've had to replace the spring, but the screw is size M8 while the eyelet on the spring arm, is only big enough for an M6. Is there another way to achieve the same function?

Any assistance would be much appreciated

mystery fastener

  • $\begingroup$ For keywords try carriage bolt and threaded spacer or threaded standoff. Most standoffs will have a different outside shape, but that's probably not critical to the application. It's possible that it's a 1/4"-20 thread $\endgroup$
    – Ethan48
    May 2, 2019 at 14:22
  • $\begingroup$ Does the rounded cap on the left have a slot or some other kind of flat for a tool? Or, is the rounded head produced by riveting? $\endgroup$ May 4, 2019 at 21:34
  • $\begingroup$ Is the screw one part or two, if one part, how did it get into the hole, if two parts can you take it apart to provide more pics? $\endgroup$
    – mart
    Apr 21, 2021 at 12:24
  • $\begingroup$ belmetric.com/… $\endgroup$
    – Phil Sweet
    Aug 20, 2021 at 22:53

2 Answers 2


There is the bolt with domed head on lhs securing the bar to the circular body. That body with flats then has a machined threaded section on the rhs.

This allows the bar to rotate or be removed separately to the other part which may secure something else.


Does not appear to be a standard fastener. Mass production quantities comparable to standard nuts and bolts would have likely opted for a hex or other extruded shape where the cylinder with what appears to be a machined flat- both to reduce material and to make it easier to handle.

As for another way to achieve the same function, you could use multiple pieces. From standard fasteners, I'd consider a shoulder bolt since it needs to behave like a shaft, a standoff. Shoulder bolts are expensive so ditch it for a regular screw if you want something cheaper. Standoff can be replaced with a coupling nut and threaded rod if you want.


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