Intake ceiling. Four diffusion panels, documented at 48" x 57.5" (polyester ceiling pad, SKU 700-282) with a Filtrair FF560GX 48" x 56" alternative (SKU 0256048564) in the same slot family. These panels set finish quality; run tacky-side-down media discipline and change them as a set.

Make-up air. The AMU stage is documented with a pocket bag prefilter at 20" x 50" (SKU 154-070) and non-tacky 3-ply link prefilters at 20" x 50" (SKU 01625205010) and 25" x 60" (SKU 0162525608). This stage is cheap insurance for the ceiling media downstream of it, so do not stretch it.

Exhaust side. The side-wall grids take 15 gram fiberglass paint arrestor pads at 20" x 20" (SKU 14AGP202050). Because the SDD splits its exhaust across two walls, the pad count is typically higher than a shop expects, and the pads nearest the turn zone load fastest. Change both walls as one set; a fresh wall opposite a loaded wall pulls the spray pattern sideways.

Every size above comes from catalog cross-reference rather than a field measurement of your booth, so treat the first order as the verification pass: count grid openings on both walls, measure one ceiling frame, and the record is locked from then on.

The regulatory frame does not care that the exhaust is in the walls instead of the floor. EPA 6H still requires refinish spraying in a filtered, maintained booth with records. OSHA 1910.94(c) still requires ventilation that captures overspray at design airflow, which on an SDD means both side grids passing air evenly. NFPA 33 still treats the arrestor pads and any residue around the grid frames as combustible deposits. The side-downdraft wrinkle is symmetry: an inspector watching smoke drift toward one wall because the other is blinded is looking at a ventilation deficiency, so log both walls' changes together.