It's peace of mind, no worries about safety. Previously I used unprotected 10440's and latterly protected 10440's (with
threads showing, they were slightly too long), but these IMR
batteries work as well as if not better than both of those - they are high drain so go well with the LR901 atomisers I prefer.
I've used carts, cartomisers and even AFS but now prefer just to carry a 5ml bottle and drip when out & about. I also have a newer Slim with extension so I've tried the 7.2V but really 3.7V is enough for me, and I like the fact these Slims are small and discrete. Battery life is quite short, but nothing a few spares in a carry case can't solve.