Eli5, why do Mason jar lids typically come in 2 parts, threads and seal, as opposed to nearly every other commonly used household container?

Question

Eli5, why do Mason jar lids typically come in 2 parts, threads and seal, as opposed to nearly every other commonly used household container?

In: 7899

Answer 1

The ring holds flat disk on during canning. Take the ring off after canning so you can see if the seal ever fails on the disk. The ring is reusable, the disk is not.