These are the replacement Pre-filters for your Beam Air.
They are packaged per 4.
They need to be replaced every 10-30 hours.
Don't forget to replace the other filters in time:
Remove the filters:
Just open the top cover of the filter and remove the box from the inside. Then take out the Pre-filter and pull on the lids on each side of the Medium efficiency filter, put this aside and repeat the same steps with the charcoal filter. The box that's left is the H13 HEPA filter.
Replace what is necessary.
Reinsert the filters in this order: From left to right.