PERFORATED CENTRE TUBE ( SPIRAL TYPE ) TO MANUFACTURE LOW MEAN PORE SIZE LARGE SECONDARY FUEL OIL FILTER TO RDSO DRG. SKDP- 3930, ALT. NIL AND CONFORMING TO RDSO SPEC. NO. MP. 0. 2600. 25, REV. 01, JULY, 2021 NOTE: ALL THE MATERIALS PARTS MUST BE PACKED IN RIGID HARD CARD BOARD CARTON BOXES CONVENIENT TO HANDLE. 25