In other words, hot masons!
Non-toxic bedwarmers…
If you have spare safe socks, you can drop the jars into socks so that in case you kick them out of bed, the glass would be contained, but I haven’t kicked one out yet! Use the 2 piece lids as they are watertight, you can shake them a bit to make sure there are no leaks when the lids are getting older.
Stay warm!
Seriously "Sensitive" to Pollution 