A vibration damper device for connecting a vibrating structure to a damper mass for forming a frequency-tuned damper assembly, said vibration damper device comprising: two or more elastomeric damper portions; a mounting frame made from a more rigid material than the elastomeric damper portions, said mounting frame extending in a main plane (yz), and presenting a pair of frame wall portions extending transversally to the main plane (yz); wherein each elastomeric damper portion extends along a main axis of the elastomeric damper portion from a base (54, L1) of the elastomeric damper portion connected to the mounting frame at the main plane to a distal end (55, L2) of the elastomeric damper portion, wherein each elastomeric damper portion presents a main part, which is located along the main axis between the base and the distal end of the elastomeric damper portion and is arranged to undergo primarily a shear deformation during damping operation of the damper device, and wherein said elastomeric damper portions comprise a first pair of elastomeric damper portions connected to the mounting frame at locations mutually spaced along a first axis (y) extending in the main plane (yz); said vibration damper device further comprising a pair of elastomeric stiffening bridges, wherein each elastomeric stiffening bridge is associated with a respective elastomeric damper portion of said first pair of elastomeric damper portions, wherein each stiffening bridge connects at least the main part of the associated damper portion to an associated one of said frame wall portions at a location along the main axis between the base and the distal end of the associated elastomeric damper portion, for stiffening the damper portion with respect to damping movements along said first axis (y), and wherein each stiffening bridge and its associated damper portion are made in one piece with each other from an elastomeric material to form an elastomeric damper body. two or more elastomeric damper portions; a mounting frame made from a more rigid material than the elastomeric damper portions, said mounting frame extending in a main plane (yz), and presenting a pair of frame wall portions extending transversally to the main plane (yz); wherein each elastomeric damper portion extends along a main axis of the elastomeric damper portion from a base (54, L1) of the elastomeric damper portion connected to the mounting frame at the main plane to a distal end (55, L2) of the elastomeric damper portion, wherein each elastomeric damper portion presents a main part, which is located along the main axis between the base and the distal end of the elastomeric damper portion and is arranged to undergo primarily a shear deformation during damping operation of the damper device, and wherein said elastomeric damper portions comprise a first pair of elastomeric damper portions connected to the mounting frame at locations mutually spaced along a first axis (y) extending in the main plane (yz); wherein each elastomeric damper portion extends along a main axis of the elastomeric damper portion from a base (54, L1) of the elastomeric damper portion connected to the mounting frame at the main plane to a distal end (55, L2) of the elastomeric damper portion, wherein each elastomeric damper portion presents a main part, which is located along the main axis between the base and the distal end of the elastomeric damper portion and is arranged to undergo primarily a shear deformation during damping operation of the damper device, and wherein said elastomeric damper portions comprise a first pair of elastomeric damper portions connected to the mounting frame at locations mutually spaced along a first axis (y) extending in the main plane (yz); said vibration damper device further comprising a pair of elastomeric stiffening bridges, wherein each elastomeric stiffening bridge is associated with a respective elastomeric damper portion of said first pair of elastomeric damper portions, wherein each stiffening bridge connects at least the main part of the associated damper portion to an associated one of said frame wall portions at a location along the main axis between the base and the distal end of the associated elastomeric damper portion, for stiffening the damper portion with respect to damping movements along said first axis (y), and wherein each stiffening bridge and its associated damper portion are made in one piece with each other from an elastomeric material to form an elastomeric damper body. wherein each elastomeric stiffening bridge is associated with a respective elastomeric damper portion of said first pair of elastomeric damper portions, wherein each stiffening bridge connects at least the main part of the associated damper portion to an associated one of said frame wall portions at a location along the main axis between the base and the distal end of the associated elastomeric damper portion, for stiffening the damper portion with respect to damping movements along said first axis (y), and wherein each stiffening bridge and its associated damper portion are made in one piece with each other from an elastomeric material to form an elastomeric damper body.