They're a CSK wood screw (They aren't machine screws), 6.3mm (or 1/4 inch) overall length, with a Phillips, not Pozi, head (although Pozi would work fine) which is 5mm Ø.
OD of the threads comes up as 2.66mm on my digi-verniers.
Good luck with finding two of those from a source other than Shimano.
Try my friends at Clerkenwell Screws on 0207 405 1215.