The Special Air Service or S.A.S. is a regiment of the British Army constituted on 31 May 1950, and is regarded by many as the best such force in the world. They are part of the United Kingdom Special Forces (UKSF) and have served as a model for the special forces of many other countries all over the world. The SAS together with the Special Boat Service (SBS), Special Reconnaissance Regiment (SRR), Special Forces Support Group (SFSG), (UKSF) Signal Regiment and the Joint Special Forces Aviation Wing form the UKSF under the command of the Director Special Forces.