Some Regiments and Corps wear a stable belt in No 8 dress whilst others restrict its use to Nos 13 and 14 Dress. On exercises and operations the stable belt is replaced with a plain green field belt, with nylon Personal Load Carrying Equipment and the Osprey body armour vest with pouches attached using the PALS system being worn for load-bearing purposes. In the twentieth century the British army introduced Tactical Recognition Flashes (TRFs) – worn on the right arm of a combat uniform, this distinctive insignia denotes the wearer's regiment or corps (or subdivision thereof, these being the ALS, ETS, RMP, MPGS, and SPS, in the case of the AGC). Working headdress is normally worn, which is typically a beret. The colour of the beret usually shows what type of regiment the wearer is from. The colours are as follows: Khaki: Mercian Regiment, Foot Guards, Honourable Artillery Company, Princess of Wales's Royal Regiment, Royal Anglian Regiment, Duke of Lancaster's Regiment, Royal Welsh, Yorkshire Regiment, Royal Gibraltar Regiment, 4/73 (Sphinx) Special Observation Post Battery RA Light grey: Royal Scots Dragoon Guards, Scottish and North Irish Yeomanry Dark grey: Queen Alexandra's Royal Army Nursing Corps Brown: King's Royal Hussars, Royal Wessex Yeomanry Black: Royal Tank Regiment, Westminster Dragoons Squadron, Royal Yeomanry Dark (Rifle) green: The Royal Dragoon Guards, The Queen's Royal Hussars (with broad browband), The Rifles, Royal Gurkha Rifles, Small Arms School Corps, Essex Yeomanry Maroon: Parachute Regiment, all ranks serving with 16 Air Assault Brigade (not restricted to Parachute qualified personnel) other than the non–Parachute Regiment Infantry Battalion or Army Air Corps and attached Arms personnel Beige: Special Air Service including attached troops who are not SAS-qualified Emerald grey: Special Reconnaissance Regiment Commando green: Commando qualified personnel serving in Commando units (including the Special Boat Service) Cypress green: Intelligence Corps Cambridge blue: Army Air Corps including attached personnel and REME Aircraft trades, 47 Regiment Royal Artillery any army personnel serving in an aviation unit. Scarlet: Royal Military Police Green: Adjutant General's Corps (except Royal Military Police, who wear scarlet; Military Provost Staff, Educational and Training Services Branch and Army Legal Service, who wear navy blue), Military Provost Guard Service Dark blue: all other Army units (except Scottish line infantry regiments and the Royal Irish Regiment) A regiment or corps cap badge is worn on the beret or other headdress worn in No. 8 Dress. The badge is positioned above