Was introduced partly as a deception to help to confuse the Germans over the use of GEE. It was nevertheless just as useful as a homing beacon. A number of transmitters, from Lossiemouth to Manston in Kent transmitted on slightly different frequencies transmitted a narrow beam across the North Sea using a S.B.A. (Standard Beam Approach) transmitter, receivers for-which were fitted to all British bombers and could be received over a range of 350 miles at 10,000 feet. Once a bomber found a beam it could fly down it back to Britain. In late 1943, all but two beams were closed down with these final two shutting down towards the end of 1944 because GEE could do the job better and their use to deceive the Germans was by now redundant.