Do SELF SEALING inner tubes work?

i seen several at walmart ranging from spray cans full of goo you spray into the tube to a liner you place in the tire before you put the tube acting as a protective liner for the tube A. do these things work? B. would the sealant be just for an emergency in case you get a flat in the middle of nowhere or do... show more i seen several at walmart ranging from spray cans full of goo you spray into the tube to a liner you place in the tire before you put the tube acting as a protective liner for the tube

A. do these things work?

B. would the sealant be just for an emergency in case you get a flat in the middle of nowhere or do they last a while?
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