A holding frame for a plug connector, namely a heavy industrial plug connector for receiving similar and/or different modules comprising a base portion for fixing a received module in a plane and a deformation portion which can assume an insertion state and a holding state, wherein the insertion state allows insertion of at least one module into the holding frame in a direction transverse relative to the plane and a received module is fixed in the holding state, wherein the base portion and the deformation portion are at least partially formed from different materials and wherein the base portion and the deformation portion (2, 2') have different material properties, namely different moduli of elasticity, wherein the base portion is a peripherally extending base frame which is of rectangular cross-sectional configuration and has two mutually parallel and oppositely disposed end faces and at a right angle thereto two parallel and oppositely disposed side portions, wherein the end faces are shorter than the two side portions, and wherein the base portion at the end faces has a respective flange projecting at a right angle relative thereto, wherein each of said flanges has two screw bores so that the base frame in total has four screw bores, and wherein the deformation portion (2, 2') is in the form of at least one cheek portion on the base frame, and at least a part of the deformation portion (2, 2') is arranged externally on the base portion, and the base portion and the deformation portion (2, 2') are positively lock-ingly, force-fittingly and/or positively substance jointingly interconnected, and wherein the deformation portion (2, 2') is designed for elastic deformation between the insertion state and the holding state, and wherein the deformation portion (2, 2') has or comprises resilient sheet and the resilient properties of the deformation portion (2, 2') make it possible to individually insert or remove modules (3, 3'), and wherein the deformation portion is at least partially produced with a stamping bending process, and wherein the holding frame has a protective earthing contact or is equipped therewith, and wherein the base portion is produced at least partially by pressure die casting, more specifically from a metal like for example zinc or a metal alloy, preferably a zinc alloy or aluminium alloy, and wherein the base portion is of lower elasticity and thus greater stiffness than the deformation portion, and wherein the base portion is stiff and the higher elasticity of the deformation portion (2, 2'), in comparison with the base portion is achieved by - the higher elasticity of the material used for the deformation portion (2, 2') in comparison to the material used for the base portion and/or - the geometrical shapes of the base portion and the deformation portion (2,2'). wherein the base portion and the deformation portion are at least partially formed from different materials and wherein the base portion and the deformation portion (2, 2') have different material properties, namely different moduli of elasticity, wherein the base portion is a peripherally extending base frame which is of rectangular cross-sectional configuration and has two mutually parallel and oppositely disposed end faces and at a right angle thereto two parallel and oppositely disposed side portions, wherein the end faces are shorter than the two side portions, and wherein the base portion at the end faces has a respective flange projecting at a right angle relative thereto, wherein each of said flanges has two screw bores so that the base frame in total has four screw bores, and wherein the deformation portion (2, 2') is in the form of at least one cheek portion on the base frame, and at least a part of the deformation portion (2, 2') is arranged externally on the base portion, and the base portion and the deformation portion (2, 2') are positively lock-ingly, force-fittingly and/or positively substance jointingly interconnected, and wherein the deformation portion (2, 2') is designed for elastic deformation between the insertion state and the holding state, and wherein the deformation portion (2, 2') has or comprises resilient sheet and the resilient properties of the deformation portion (2, 2') make it possible to individually insert or remove modules (3, 3'), and wherein the deformation portion is at least partially produced with a stamping bending process, and wherein the holding frame has a protective earthing contact or is equipped therewith, and wherein the base portion is produced at least partially by pressure die casting, more specifically from a metal like for example zinc or a metal alloy, preferably a zinc alloy or aluminium alloy, and wherein the base portion is of lower elasticity and thus greater stiffness than the deformation portion, and wherein the base portion is stiff and the higher elasticity of the deformation portion (2, 2'), in comparison with the base portion is achieved by - the higher elasticity of the material used for the deformation portion (2, 2') in comparison to the material used for the base portion and/or - the geometrical shapes of the base portion and the deformation portion (2,2'). - the higher elasticity of the material used for the deformation portion (2, 2') in comparison to the material used for the base portion and/or - the geometrical shapes of the base portion and the deformation portion (2,2').