Here is a little good info for those looking into the "lifetime" tanks from Immortal and first strike. Just the measurements from AMS website. Both FS and Immortal use the same tanks. And as you probably know, they're not lifetime, but after they've been hydro'd as normal every 5 years, they don't "die" at 15. They can be sent out and re-certified by the manufacturer for a full service life of 38(39?) years. 
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