https://www.ebay.com/sch/i.html?_nkw=Allegro+9878+50+Filter+Kit+For+Mfr+No+9878&_sacat=0&_dmd=2

Allegro 9878-50 Filter Kit, For Mfr. No. 9878

Regular price
$225.00
Sale price
$154.00

Replacement Filter Kit, For Use With 100 cfm Carry-Air(TM) and Wall-Air(TM) Filtration Panels, Includes (2) 1st Stage, (1) 2nd Stage, and (1) 3rd Stage Filter