Connection device for the mechanical connection of an electronics housing, specifically a protection housing for an electronics unit, specifically a transmitter electronics unit, and a transducer housing, specifically a protection housing for at least a sensor element, particularly physical to electrical, said connection device comprising: - a connection nozzle, particularly tubular and/or formed by means of a metal tube, with an interior channel surrounded by a nozzle wall, particularly metal and/or at least partially hollow cylindrical; - as well as a tubular cable duct, formed particularly by means of a metal tube or a metal hose, with an interior channel (32*) designed to guide electrical connecting cables, said interior channel being surrounded by a duct wall and extending from a first duct end (32+) to a second duct end (32#) at a distance therefrom; - wherein the nozzle wall or the connection nozzle formed with said wall has a first opening (31+) and a second opening (31#) at a distance therefrom; - wherein the cable duct and the connection nozzle are arranged in such a way that -- the cable duct is partially positioned in the interior channel of the connection nozzle and is partially accommodated by both the first opening in the wall of the connection nozzle and by the second opening in the wall of the connection nozzle, -- and that a cavity, specifically a single cavity and/or a cavity formed as an open ring junction, is formed between an interior surface of the nozzle wall facing towards the interior channel and a lateral surface (321") of the duct wall facing towards the interior channel; - and wherein the cable duct and the connection nozzle are interconnected, particularly via a substance-to-substance or adhesive connection, in such a way that the cavity is closed in a gas-tight manner, particularly at least in an airtight manner, specifically in such a way that the cavity is hermetically sealed against an atmosphere surrounding the connection nozzle or the connection device. - a connection nozzle, particularly tubular and/or formed by means of a metal tube, with an interior channel surrounded by a nozzle wall, particularly metal and/or at least partially hollow cylindrical; - as well as a tubular cable duct, formed particularly by means of a metal tube or a metal hose, with an interior channel (32*) designed to guide electrical connecting cables, said interior channel being surrounded by a duct wall and extending from a first duct end (32+) to a second duct end (32#) at a distance therefrom; - wherein the nozzle wall or the connection nozzle formed with said wall has a first opening (31+) and a second opening (31#) at a distance therefrom; - wherein the cable duct and the connection nozzle are arranged in such a way that -- the cable duct is partially positioned in the interior channel of the connection nozzle and is partially accommodated by both the first opening in the wall of the connection nozzle and by the second opening in the wall of the connection nozzle, -- and that a cavity, specifically a single cavity and/or a cavity formed as an open ring junction, is formed between an interior surface of the nozzle wall facing towards the interior channel and a lateral surface (321") of the duct wall facing towards the interior channel; -- the cable duct is partially positioned in the interior channel of the connection nozzle and is partially accommodated by both the first opening in the wall of the connection nozzle and by the second opening in the wall of the connection nozzle, -- and that a cavity, specifically a single cavity and/or a cavity formed as an open ring junction, is formed between an interior surface of the nozzle wall facing towards the interior channel and a lateral surface (321") of the duct wall facing towards the interior channel; - and wherein the cable duct and the connection nozzle are interconnected, particularly via a substance-to-substance or adhesive connection, in such a way that the cavity is closed in a gas-tight manner, particularly at least in an airtight manner, specifically in such a way that the cavity is hermetically sealed against an atmosphere surrounding the connection nozzle or the connection device.