Should rephrase that m12to m10 reducer inserts as I had to remove tap a hole 12mm but the bolt is 10mm
See here.
They are ok, used them a few times.
Your cheapest option would be an EZLOK thin wall insert M10x1.5/0.5"x13tpi (UNC)
Not sure the hole has already been drilled..if it has then just go for the 0.5"x20tpi model which would require an 11.9nn drillWhat does the data sheet say the tapping drill size for this insert is? If less than 12mm, it is not suitable as the hole already there is that size.