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Originals appear to be countersunk M3, with 0.5mm pitch and 16mm length.
GiGDigit - Screw for Heat Bed Leveling
M3 x 16mm Metric Hex Socket Countersunk Flat Head Screw Bolts 50PCS
https://www.amazon.com/dp/B018RSXSLE
Black Oxide Coating Class 10.9 - 100 pk
http://www.mcmaster.com/#91294A134
316 Stainless - 100 pk
http://www.mcmaster.com/#93395A210
High Visibility Blue Class 10.9 - 50 pk
http://www.mcmaster.com/#91304A104