Beach RC says... This is the Ultimate Racing
pre-oiled dual-stage foam air filter, and it's been specially designed
for use with Ultimate Racing air filter. The combination of this
pre-oiled foam air filter with the Ultimate Racing air filter
oil guarantees the maximum air flow and offers an excellent air
filtration and protection for your engine. Available in economic packs
of 6 or 12 pieces pre-oiled and safely stored in a double zipper bag, so
can be stored for long time and ready to use when you need them.