https://www.gobilda.com/m4-button-head-screw-assortment-pack-600-pcs/

Lower-profile button head screws can give you that extra bit of clearance. This back includes 6mm, 8mm, 10mm, 12mm, 16mm, and extra-long 55mm screws along with regular hex nuts, nylock nuts, washers, and lock washers. Note that M4 button head screws use a 2.5mm hex driver, not a 3mm hex driver.