This item is WWII German original emergency transmitter \"Notsendegerat\" NS4 a (Notsende-Gerat 4 (NS4), somtimes NSG 4),code-name \'Jager\' (Hunter), developed by Loewe-Opta in 1941. It could be worn attached to the pilot\'s suit. The NS 4a transmitted on 58,4 - 58,8 MHz with 0,3 W. Two other versions of NSG 4 , the NSG 4 c and NSG 4 d, having the same physical shape, transmitted on 42,0 - 42,5 MHz. The receiver used for the homing procedure with NS4 a was the FuG 141.The NS4 and NS4a (c) sets were painted the usual bright yellow and are hermetically sealed. When not in use, it was normally detached from its baseplate and worn in the left pocket of the flying suit trousers (affectionately named \'Kanalhose\').The transmitter operated automatically when the 4ft long steel tape aerial was completely unrolled from the set, sending a continuous tone modulated signal. The condition of the item is great.