Help me choose Brembo brake and clutch master, 16x18 or 19x18 or 19x20 please,

[hayachan]

Hi,

I'm in for brembo brake and clutch master,
Ask the shop and he said i should go for 19x20 for brake and 19x18 for clutch master, I kinda confuse since i have absolutely no clue about what those number do, Want some opinion if i should go with what he said.

Cheers