Roundabout

R137

Where: On any road where there are multiple roads intersecting.
Purpose: To indicate that you must move in a clockwise direction at the junction.
Action: Yield right of way to vehicle approaching from the right within the roundabout, where such vehicles are close enough to cause a danger or potential danger. Proceed clockwise at the junction if it is safe to do so. Version 1.00 10 Jun 2012 Copyright © 2012 by SA Department of Transport

Manual on Road Traffic Signs, page 11.