A sector part of a filtering, preferably rotating, disk comprising: a relatively stiff and rigid support (1; 12) for transport of liquid there through, the support (1; 12) being centrally located in the sector part; a substantially sealing edge (2; 22) having one or more fluid discharges; and a first portion and a second portion of finely perforated net type material (3, 4; 32, 42), the first portion positioned on a first side of the sector support (1; 12) and the second portion positioned oppositely disposed from the first portion on a second side of the sector support (1; 12), the finely perforated material (3, 4; 32, 42) adapted for capturing and separating of fibres and/or of particles from a mixture of fibres and/or particles and fluid, characterized in that each of said first portion and second portion of finely perforated material (3, 4; 32, 42) is held mainly loose and movable relative to the support (1; 12) and at least partly movable relative to the sealing edge (2; 22) in a main plane of each of the first portion and second portion of finely perforated material, and parallel to a main plane of the sector part and in that each of the first portion and the second portion of finely perforated material is fixed together by holding means (5; 52; 32a) extending essentially perpendicular to the main plane of the sector part and that a part of the holding means passes through the said first portion and second portion of finely perforated material (3, 4; 32, 42) in slightly larger holes than actually required for the through running parts of the holding means, so that the finely perforated material will not be repressed in any significant degree when exposed to different working conditions and to potentially generated movements. a relatively stiff and rigid support (1; 12) for transport of liquid there through, the support (1; 12) being centrally located in the sector part; a substantially sealing edge (2; 22) having one or more fluid discharges; and a first portion and a second portion of finely perforated net type material (3, 4; 32, 42), the first portion positioned on a first side of the sector support (1; 12) and the second portion positioned oppositely disposed from the first portion on a second side of the sector support (1; 12), the finely perforated material (3, 4; 32, 42) adapted for capturing and separating of fibres and/or of particles from a mixture of fibres and/or particles and fluid, characterized in that each of said first portion and second portion of finely perforated material (3, 4; 32, 42) is held mainly loose and movable relative to the support (1; 12) and at least partly movable relative to the sealing edge (2; 22) in a main plane of each of the first portion and second portion of finely perforated material, and parallel to a main plane of the sector part and in that each of the first portion and the second portion of finely perforated material is fixed together by holding means (5; 52; 32a) extending essentially perpendicular to the main plane of the sector part and that a part of the holding means passes through the said first portion and second portion of finely perforated material (3, 4; 32, 42) in slightly larger holes than actually required for the through running parts of the holding means, so that the finely perforated material will not be repressed in any significant degree when exposed to different working conditions and to potentially generated movements.