I saved these specimens from disposal in the 1980s. There are no markings on the black housing, so they are either experimental specimens or prototypes. Based on the literature (retrodekan.eu), I estimate that these are trial copies / prototypes of TG1-TG5 transistors and were made at the Institute of Telecommunications. Mass production of TG1-TG5 transistors was already carried out at TEWA and in a different housing. The copies are in working order.