Levo Gen 3 Bolt size for calliper

[Tyjay]

afternoon all
noticed today that back brake had some play in it (calliper)
which was caused by loose front bolt. So tightened it but felt like it was ready to strip if I went too tight
removed bolt and the bottom of threads are worn
what size bolt is it I need so I can order a new one
it is 40mm in total length m6?

any direct link appreciated. All my spares are too short there all direct mount

thanks

 

[Mikerb]

cap bolt length is measured from the bottom of the cap.
What size Allen fits the bolt?
If 3 then its a M4 bolt
If 4 M5 bolt
If 5 M6

 

[Tyjay]

cap bolt length is measured from the bottom of the cap.
What size Allen fits the bolt?
If 3 then its a M4 bolt
If 4 M5 bolt
If 5 M6

5mm Allen head
Iv ordered some m6 from halfords for the extorinate price of 1.90 for 2
but gonna sort out some coloured bolts aswell