Screw dimensions for attaching internal battery.

I have bought a refurbished t480 thinkpad which came with only an external battery, no internal one installed.

I want to install an internal battery, but I don't have any screws.

This guide [ Lenovo ThinkPad T480 내부 배터리 교체 ] mentions "the two 4.6 mm screws securing the internal battery to the frame".

I'm assuming 4.6 mm is the length, can anyone help me with pitch or gauge? Or are they M# something or another style where all that is standardised?
Or any idea where I could look for a part number?

Thanks, any hints greatly appreciated!