Rear Caliper

[JoeRock]

Just noticed today that it has two bleed nipples, seeing as it has only one hose, how on earth does that work? I've never seen one with twin nipples and when I bled it last time didn't do both, which might explain why it doesn't feel particularly useful!
Or is it there just to make life easier when bleeding?

[Fazerider]

One for the left cylinder, one for the right.
Slackening the banjo at the top of the master cylinder can help release any air bubbles that get trapped there.

[elbrownos]

You need a bleed nipple at the highest point.
The rear caliper has two highest points so needs two bleed nipples. It is impossible to bleed the caliper properly with only one nipple.

[Dead Eye]

To answer why it makes sense;

There is a channel bored through each caliper with an O-Ring between the two halves - this allows the fluid to get from one side of the caliper to the other with only one line feeding it

[unfazed]

All woman have them