what is the shelf life on knox gelatine especially the kind in the can I should note after opened

Dry gelatine in powder form has an indefinite shelf life if stored under clean, dry and well ventilated conditions. During the first year after manufacture it may loose up to 5 % of its gel strength and after that, loss of gel strength over the next 4 years can also be 5 % but thereafter loss of gel strength virtually ceases. There is one exception that must be mentioned. If dry gelatine is stored in a fairly new kitchen cupboard the formaldehyde from the adhesives used in the cupboard can react with the gelatine rendering it insoluble in water. For this reason, and because gelatine is often stored for long periods, it is recommended that gelatine should be transferred into a well sealed glass container as soon as possible after purchase. Prolonged heat and moisture (ex: refrigeration) will degrade gelatin if stored improperly. The bottom of my recently purchased 16 oz. can has an expiration date of 2/18. So with that noted opening the can does not appear to affect the gelatin if stored and sealed properly as stated but there will eventually be some loss of quality as time passes.

Is this item actually for 12 16oz containers?

The listing I'm looking at still says 12 16 oz containers and shows a photo of a case of 12. I am so glad you asked this question--I wondered how the price could possibly be that low--am glad for the answers that indicate it is just one. Don't know how they get away listing it as a case of 12?!?!

What is it made from if not beef?

Please note that you can buy gelatin made only from beef. I don't know if there is any health or purity difference between beef-only gelatin and gelatin from a variety of sources, but beef-only gelatin appears to be more costly to buy. Here is one explanation of how gelatin is made: " Gelatin is a yellowish, odorless, and nearly tasteless substance that is made by prolonged boiling of skin, cartilage, and bones from animals. It's made primarily from the stuff meat industries have left over — we're talking about pork skins, horns, and cattle bones."

how to open the bottle？

Use a sharp knife to cut/slit the plastic cover between the lid and the jar. Remove the plastic covering from the jar lid, and discard. Then open the jar. Then the orange plastic film will not be annoying for future use.