The filter in your H-P Filtered Cyclonic power unit should be replaced once a year. 10" Filter fits all H-P Products Filtered Cyclonic Power Unit models including:
VACUFLO models: FC300, FC310, FC520, FC530, FC540, FC550, FC550-C, FC610, FC620, FC650, FC650-C, FC670, FC1550
Dirt Devil models: 299e, 499e, 599e, 599e-C, 799e, 799e-C, 1099e, 390, 590, 690, 690-C, 890, 990, 990-C, CV2200, CV2250, CV2600, CV2650, CV1800, CV1850
Royal models: CS400, CS620, CS620-C, CS820, CS820-C
Vroom models: FC25, FC35C, FC55, FC65, FC65C
Titan models: TCS 5525, TCS 8575