This is for Glass Canning jars and it is a two piece metal that vacuum seals when water bathed correctly.
You can purchase lid's with bands in a box or just lids or just band's. Most jar's you buy will come with a band and lid for each jar. You can reuse the band's as long as they are not rusted, scratched, nicks, or uneven rims or damaged. They should slide right on the jar.
The lid's are not reusable but can be recycled in many way's.
The picture at your right shows my heating tool's when canning. I have a small stainless steel pot that I use to heat the lid's. You do not want to warm them in boiling water because the rubber will not seal correctly.
The rubber is what the pro's call the sealing compound and this is what keeps the jar's sealed and the product you are canning from spoiling. If you over heat it it will not seal. I will put my lids in my little pot with the hot water right when I am ready to fill my jar's this way they are warm and ready right after I wipe the rims of the jar's then we seal.
You just need to heat them with water that is hot not boiling. The standard is 180 degree's.
I also have a post on way's you can
recycle and reuse your lids.
It is just one more way to use everything.
Ahh I can hear Granma Mimi now.
"Waste Nothing my dear one"
Disclaimer: This is not an all inclusive recipe for making jam. You should have a basic knowledge and understanding of the canning process before proceeding. Please consult your local Center for Home Preservation for additional information and available classes.