Brompton Chainring Bolts for Detachable Chainring - Pack of 5

Hi, What's the thread on the hidden bolt please?... I'm looking to put a Campagnolo 5-arm-pattern Record Ultratorque crank on my Brompton Nickel and I'm looking for options to fit single ring chainrings to the Campy arms... and the hidden bolt on Campy carbon arms is M8x0.75 (thanks a bunch Campagnolo)... I've got the kit to make my own screws if I have to, but having had to make a set when I put a Centaur Ultratorque crank in my H11 I know it would be easier to just buy them rather than spend a day bent over a lathe making three scrap screws for each good one I managed...