Le Parfait Familia Wiss jars are a mason style jar and in our opinion one of the best preserving jars on the market.
The glass is heavy duty and the closure is a 2 piece lid, consisting of a flat disk with a seal and pop top (in the 2 smaller sizes) and a screwtop lid with inverted dome.
When heat processing the jars, the poptop on the disc aligns with the inverted dome on the lid and this helps keep the lid in place during processing and minimising the chance of seal failures.
The disc part of the lid is single use if heat processed but the screw lid can be reused and also serves as a storage lid once the jar has been opened. Once heat processed food has cooled, the screw lid should be removed from the jar and left off so that any seal failures are easily identified.