 Until the late 1990s candidates for the SAS and SBS underwent selection under the auspices of the prospective unit.Selection is reported to be one of the most demanding military training courses in the world with a reported pass rate of less than 10%.It is a test of strength, endurance, and resolve over the Brecon Beacons and Elan Valley in Wales, and in the jungle of Belize, taking around six months to complete.