filter sponge

sponge grenade / projectile

rammer and sponge

polyurethane foam sponge

sponge rubber

band-pass filter / bandpass filter (BPF)

dust filter / dust shield, particle filter

dust shield / dust filter, particle filter

filter housing / filter unit

filter unit / filter housing

particle filter / dust shield, dust filter

finite impulse response filter (FIR-filter)

passband filter; bandpass filter (BPF)

air filter

filter-separator

fuel filter

gas-particular filter unit (GPFU)

home-made face filter

individual portable filter

oil filter

RF interference filter

filter stack

military-grade filter

slave oil filter

bag filter

bath filter

centrifugal oil filter

disk filter

air defense filter center

engine filter

filter cap

filter center

filter head