depends on the make of the parts used. I had 8 mm nipples on the rear brake cylinders and 11mm nipples on the front discs.
Agree with everyone here on a few items (and a few I added from experience):
1. Open ended and shifters are the worst thing you can use when bleeding brakes;
2. Yes ze Germans used metric exclusively, unless some muppet put on other fasteners;
3. Invest in a bleeding kit that has a clear hose, thats how you can easily see that no air is in the lines;
4. overpurchase your brake fluid so you can make sure you don't run out, and finally;
5. top up the reservoir regularly to ensure you aren't putting more air into the system.
2016 Skoda Octavia Scout 110kW TDI Manual - Quartz Metallic Grey (Czech Panzer)
1998 Golf Cabriolet Manual - Black Magic Pearl (aka Rommel's Panzer) Deceased/written off
1993 Golf Cabriolet Manual - Alpine White (aka Hitler Youth Wagen) Deceased/written off
1976 Golf LS Manual - Bronco Brown (aka Roadrunner) Deceased/worn out