GAMMA SEAL LIDS. LOW AS $5.80 EACH. GAMMA2. GAMMA SEALS WAREHOUSE DIRECT

The Gamma Seal lid permanently transforms your 12" diameter bucket into a storage container. Now a bucket can be used for hundreds of household and other storage applications! Simply snap the patented adapter onto your bucket and spin-on the removeable lid. Specially engineered gaskets ensure that the lid and adapter are properly sealed to ensure almost-airtight protection. I have many of these at home and they keep things organized. I have one for cat food, one for my rock salt, one for lawn fertilizer, one for a diaper pail, one on the boat, and a few others.
All you do is snap the adapter onto your pail, spin on the lid, and that's it. One quick spin and it's open, closes in seconds! No more prying off those difficult lids.
The Gamma Seal lid fits virtually any 3.5-7.0 gallon standardized paint/drywall compound plastic bucket (including 20 liter).  We also sell the buckets (pails).   Although we don't make any recommendation, people use them for:

Food Contact Information From The Manufacturer:
The Gamma Seal Lid: the raw material used in manufacturing is Formolene LH5206, High Density Polyethylene (HDPE).
Formolene LH5206 meets all requirements of the U.S. Food and Drug Administration as specified in 21CFR 177.1520, covering safe use of polyolefin articles intended for direct food contact. 
The gaskets for the lid and the adapter are made from SBR (styrene-butadiene Rubber copolymer) and coated with an FDA approved silicone lubricant.  The pigments used in manufacturing are heavy metal free.
Gamma Seals and Pails are BPA-Free.