The largest cartridge in the Core line, and the one people most often try to replace with a smaller one.
The Core 400S is the largest machine in the Core line and takes the largest cartridge. Core 400S-RF and Core 300-RF are physically different parts, and the fact that both listings describe a genuine Levoit filter with AHAM Verifide status and activated carbon does not make them interchangeable.
A larger machine moves more air, and a cartridge in one accumulates load faster at the same running hours than a smaller machine would. That is a scheduling consequence rather than a purchasing one.
No third-party listing for this code is stocked here. Where that leaves a gap, the answer is to look for a listing that names the Core 400S-P — not to reason from a number that looks close.
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Genuine
Sold by the company that built the machine. The compatibility statement comes from the party who designed the airflow path.
Levoit Core 400S-RF Filter
The genuine cartridge for the Core 400S-P, which is the larger machine in the Core line and takes a correspondingly larger filter. The listing states AHAM Verifide status and activated carbon. Core 400S-RF and Core 300-RF are not interchangeable regardless of how similar the packaging looks on the shelf.
What the listing supports, and what it does not
Model code is stated explicitly, so it can be matched against the old cartridge
Genuine Levoit part rather than a compatibility claim from a third party
AHAM Verifide status is stated in the listing
Activated carbon is stated as part of the assembly
Fits the Core 400S-P only according to the listing, and will not stand in for a 300-series cartridge
A single cartridge per order
Larger machines get through filters faster simply because they move more air
Best forA Core 400S-P that needs the part the machine was built around.
Fit is asserted by the seller, not by the appliance manufacturer. Read the named model list against the label on your own machine.
This catalog stocks no third-party listing for Core 400S-RF. That is a statement about what is here, not a statement that none exists — and it is not a reason to reach for a cartridge named for a different code.
The machines these listings name
1 entry sits below, drawn from 1 genuine and 0 third-party listings for Core 400S-RF. Each one is here because a listing names it, and no numbering pattern has been read as a compatibility claim.
Levoit Core 400S-P (stated by the genuine listing)
How to check your own
Open the filter door and take out the cartridge — the code is on the plastic rim.
Read the whole code: the 400S cartridge is visibly larger than a 300-series one, but the printing is what confirms it.
Check the machine label against the machine named in the listing.
The sticker inside the filter compartment repeats the part number if the cartridge printing has faded.
When it gets changed
Levoit publishes an interval for the Core 400S and the machine tracks running hours toward it. A larger machine in a busy room gets there faster than the stated interval assumes, and heavy pet or smoke load shortens it further.
To repeat what is said at the top of the page: the Amazon links here are affiliate links and may earn this site a commission. Ordering, badges, and every claim on the page were decided from what the listings state, not from any commercial arrangement.
