This is what makes SAS selection the toughest in the world | We Are The Mighty

The Special Air Service accepts only the top candidates and puts them through a grueling selection school in order for them to earn the title of “Blade.” Their training programs include timed marches, treks through the jungle, and mountain climbing. They only run two selection courses a year, and candidates are usually pulled from the British Special Forces, light infantry, airborne, and commando units. The selection lasts for five months and pushes candidates to their limit, having over a 90% dropout rate.

Source: https://www.wearethemighty.com/makes-sas-selection-so-tough