First one is "large" model (1870 Russian post and telegraph department standard), second is "small" model (1864 Russian post and telegraph department standard), third one is a telephone/wall-mounted model. The initial design appeared in 1864 and was based around Preussian 1862 Doppelglocke but with additional fail-safe measure, the "ears" (a piece of wire was inserted into these ears to facilitate lineman's work and prevent the wire from dropping to the ground in case of bandage failure).