AERAMAX PRO 3/8" CARBON FILTER WITH PRE FILTER BLACK 4/PKThe AeraMax 9416502 PRO III and IV 3 8" carbon air filter with prefilter provides approximately 6 months of service life. It's designed for use with the AeraMax PRO III and IV air purifiers, trapping a variety of volatile compounds from the air and removing odor for a more comfortable environment. Activated carbon makes this possible, while the prefilter helps capture larger particulates so the carbon filter performs better and lasts longer. Overall