Blue plastic frame for sandwiching the post filter. This is a two piece assembly, a front grid that snaps to the rear grid. The postfilter frame mounts right behind the collector cell
The overall size of the frame assembly is 13¼ x 17.
To remove the frame, there are two latches that need to be released by using a flat screwdriver. The latches are accessible through two slots where inserting a screwdriver will release the latch. First release one latch, then lift that side of the frame just a slight amount and move the screwdriver to release the second latch.
After the frame is removed, the postfilter is removed by separating the front and rear grid. The front and rear grid snap-in place with a ratcheting latch. Viewing the frame from the backside will reveal the four latch mechanisms. Spreading the inner frame from the outer frame will release the latch.