This is a BMW hydraulic accumulator, direct replacement for Ferrari 158693, though the mount bracket is different as seen in the photos.
Does your Ferrari 456GT/ GTA, 456M or M GTA ride rough? Then you need two new accumulators. Internally, there’s a flexible bladder that ruptures. When new, one side of the sphere is nitrogen at high pressure, the other side fills with hydraulic oil. Because the shock is completely full of oil, the accumulator is needed for oil displaced by the chrome shock rod during bump.
Shocks can actually explode (rupture the aluminum body) due to hydro-lock condition brought on by non-functional accumulators.
© 2017 Delta Vee Motorsports LLC, Kalamazoo, MI