Luci Arial asked about screw-on lids for grain storage buckets. What you
are describing sounds like the Gamma Seal Lids that I have purchased from
www.azurestandard.com. The Gamma Seal Lid transforms a 3.5 to 7 gallon
bucket into an easy-to-open airtight and leakproof storage container. It is
made of food-grade high-impact-resistant plastic. The entire lid looks
much like an ordinary lid with a 12-inch screw down center. The adapter
looks like a large ring. Simply pound the adapter onto the bucket with a
mallet. Spin on the gasketed lid. To open, spin left and lift. The cost
is $5.15.
Heather Reseck, R.D.
Author of The Fix-it-Fast Vegetarian Cookbook