For general-use air filtration in 74-1800A and 74-1800W fume extractors, this 24" (61 cm) x 24" (61 cm) x 4" (10.2 cm) pre filter provides the 4" (10.2 cm) of pre-filtration required by the main unit. It functions as a single 4" (10.2 cm) filter or can be used alongside 2" (5.1 cm) filters to meet system specifications.

For general-use air filtration in 74-1800A and 74-1800W fume extractors, this 24" (61 cm) x 24" (61 cm) x 4" (10.2 cm) pre filter provides the 4" (10.2 cm) of pre-filtration required by the main unit. It functions as a single 4" (10.2 cm) filter or can be used alongside 2" (5.1 cm) filters to meet system specifications.