Laser head 10W and toolhead plate

Which screws should be used, M4 x 6 or M4 x 8, when mounting the toolhead plate on the 10W laser head?

Last week I got my extra Toolhead plates, they come with M4x6 screws, and I used those. I did not look closer, but my feeling is, the the x6 screws are going into the 10W housing exactly as deep as the x8 did before when directly mounted to the rail. Therefore, I’d strongly discourage the use of M4x8 screws, since they likely will damage the fan and subsequently the whole module.

Thank you very much. I used the x6 too