What spec topcap do I need for my bike?

[Akelu]

I recently bought a handlebar kiox mount so I can move it off of the stem topcap mounted position.

I undid the bolt of the kiox stem mount to reveal a little area that looks around an inch deep and has a kind of star pattern at the bottom. (Pic below).

I know it's all metal (not carbon), and that the stem mounts onto the fork with 1 1/8"(28.6mm).

What spec topcap do I need that will fit the cavity that the kiox mount has left?

Thanks!

 

[KennyB]

That is a star fangled nut and is the standard way of pre loading the head set bearings before tightening the stem bolts.
Any standard top cap and bolt will be ok.