Prefilter compatible with for A10 a11 hero A10 a11 master cordless vacuum cleaner Prefilter is very important for suction and suction efficiency. You need to deeply clean or replace the filter regularly to prevent suction loss. The pre filter can be flushed. Please flush it with cold water and reinstall it after it is completely dry. Replace the filter every 2 to 3 months. Depending on the frequency of use, it can be replaced for a shorter or longer time. The filter keeps the robot clean and reduces the penetration of dust, pollen and other into the air you breathe. colour: gray Material: plastic Package Contents: 5 x Vacuum cleaner filter Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.