This kit includes five 90 mil tan 5-gallon buckets with a black Gamma Seal lid for each bucket. 90 mil bucket made from FDA compliant High Density PolyEthylene (HDPE). A Gamma Seal lid adapts the bucket to a threaded spin-on / spin-off lid. The Gamma Seal is customer installed but may be pre-installed on the bucket for shipping efficiency. A rubber mallet (not included) is useful for installing the threaded ring to the bucket. The ring seals to the rim of the bucket with an O-ring gasket. The threaded lid portion then spins on and off sealing to the ring with another O-ring gasket. The O-ring gasket has a food grade silicone lubricant the helps the O-ring not to grab the plastic sealing surfaces. If this lubricant is removed through excessive cleaning, the O-ring can grab and stretch and lose it's retention to the lid. Plastic containers are rarely true. Leaving the lid snug for a period of time and allowing the several components to true to each other in a warmer room temperature environment can help with performance. For long term food and liquid applications we recommend a conventional snap-on lid with a gasket. The Gamma Seal shines in it's convenience. We like the Gamma Seal for applications requiring convenient frequent access. Gammas Seals are user installed but may be pre-installed for shipping efficiency.