Brake caliper hex bolt size?

[will89]

Planning on changing the front discs and pads tomorrow, however I'm unsure what site the hex bolt is to remove the caliper? Also in which direction does the piston twist back in? The car is a 130 tdi.

Thanks,
Will.

 

[stu_m]

I'm sure they are 13mm you may need a 15mm on the slide to steady that


Edit: piston just pushes in its the rears you need to twist