A spring structure including at least two masses (Ma, Mb) coupled as opposite phase oscillators along an axis of motion in a first direction by means of springs (Sh1, Sh2) extending in the first direction, said springs being stiff in the first direction and yielding in the direction perpendicular to the first direction, and a spring substructure (Sl45, L, E, Sr45) that couples said springs (Sh1, Sh2) to each other, in each of the springs (Sh1, Sh2), one end of the spring is coupled to one of the at least two masses (Ma, Mb) and the other end of the spring is coupled in a coupling point to the spring substructure (Sl45, L, E, Sr45); the spring substructure (Sl45, L, E, Sr45) includes a U-shaped loop (L, E) formed of two branches, and an end part between them, wherein an end opposite to the end part of a first branch of the U-shaped loop (L, E) is connected directly in a first coupling point to a first spring of said springs, and an end opposite the end part of a second branch of the U-shaped loop (L, E) is connected directly in a second coupling point to a second spring of said springs; characterized in that: the spring substructure (Sl45, L, E, Sr45) includes oblique springs (Sl45, Sr45), wherein one end of a first oblique spring is connected directly in the first coupling point to the first spring and to the first branch of the U-shaped loop (L, E), and the other end of the first oblique spring is connected directly to a first anchor of the base, and the first oblique spring yields at an oblique angle in relation to the first direction and perpendicularly to its own longitudinal axis; one end of a second oblique spring is connected directly in the second coupling point to the second spring and to the second branch of the U-shaped loop (L, E), and the other end of the second oblique spring is connected directly to a second anchor of the base, and the second oblique spring yields at an oblique angle in relation to the first direction and perpendicularly to its own longitudinal axis; the first anchor, the second anchor and the U-shaped loop are on the same side in respect of the springs (Sh1, Sh2); and the first and second anchors are on opposite sides in respect of the U-shaped loop; whereby motion of the U-shaped loop (L, E) is arranged to occur in a longitudinal direction that is perpendicular or substantially perpendicular to said first direction, to thus attenuate oscillations of the masses (Ma, Mb) other than opposite phase oscillations of the masses (Ma, Mb). the spring substructure (Sl45, L, E, Sr45) includes oblique springs (Sl45, Sr45), wherein one end of a first oblique spring is connected directly in the first coupling point to the first spring and to the first branch of the U-shaped loop (L, E), and the other end of the first oblique spring is connected directly to a first anchor of the base, and the first oblique spring yields at an oblique angle in relation to the first direction and perpendicularly to its own longitudinal axis; one end of a second oblique spring is connected directly in the second coupling point to the second spring and to the second branch of the U-shaped loop (L, E), and the other end of the second oblique spring is connected directly to a second anchor of the base, and the second oblique spring yields at an oblique angle in relation to the first direction and perpendicularly to its own longitudinal axis; the first anchor, the second anchor and the U-shaped loop are on the same side in respect of the springs (Sh1, Sh2); and the first and second anchors are on opposite sides in respect of the U-shaped loop; one end of a first oblique spring is connected directly in the first coupling point to the first spring and to the first branch of the U-shaped loop (L, E), and the other end of the first oblique spring is connected directly to a first anchor of the base, and the first oblique spring yields at an oblique angle in relation to the first direction and perpendicularly to its own longitudinal axis; one end of a second oblique spring is connected directly in the second coupling point to the second spring and to the second branch of the U-shaped loop (L, E), and the other end of the second oblique spring is connected directly to a second anchor of the base, and the second oblique spring yields at an oblique angle in relation to the first direction and perpendicularly to its own longitudinal axis; the first anchor, the second anchor and the U-shaped loop are on the same side in respect of the springs (Sh1, Sh2); and the first and second anchors are on opposite sides in respect of the U-shaped loop; whereby motion of the U-shaped loop (L, E) is arranged to occur in a longitudinal direction that is perpendicular or substantially perpendicular to said first direction, to thus attenuate oscillations of the masses (Ma, Mb) other than opposite phase oscillations of the masses (Ma, Mb).