Hallo Waken !!!
The ESAC 250/IX cartridge was a device for dropping bombs.He111 standard bomber was equipped with eight ESAC 250 in its internal bomb bay.Certainly, ESAC 250 is an abbrreviation and it stands for (in German) Elektrische-Senkrecht-Aufhangung fur Cylinderbomben 250/IX, in English - an electric activated vertical bomb rack system mark IX for cylindrical bombs up to 250 kg.
It was possible to load into the cartridge one 250 kg bomb or 4*50 kg using an adaptor or four adaptors Gr4 C10/VII with 16 bombs 10kg in each of them.Besides, ESAC 250 was adapted for loading four containers BSK-36 for one kilogram incendiary bombs B1EI.Each of them contained 36 bombs.
best regards.