Replacement bolt for Out-front Bike Mount

Sup guys!

I have a standard Out-front Bike Mount and its bolt (the one that closes the mount in the handlebar) is getting pretty oxidized, and I'm looking to get a titanium one from Aliexpress. It seems to be an allen M3x12mm cylindrical head but I'm not sure of it since I dont have pachymeter to measure. Does anyone know what's the correct specification of that bolt? Thanks