Had an eGo style battery with a mini Aerotank 3 (or something like that) which took a 40'+/- fall from a JLG lift when I bent over to get a tool from my tool bag. I learned quick to not carry in my shirt pocket any more.
I know the SS sleeve Vs. the glass would not have made a difference in my case
Yes, I'm sure there are some harsh environment where this would be handy. But not being able to see the juice level with taking it apart would be a PITA. Anytime I leave the house with a PV, I always check the juice level.