"T" and "K" are for many suppliers obsolete, and can vary depending on supplier.
The compressed gas business is full of magical pricing, policies on a whim, and some pretty odd characters.
Tobin
I'll cosign that! I lease a couple of T's of Technical Diver Grade He from my local supplier. One year - I paid $175 for a full T (about 291 cf of He at 2640 psi of 99.995 He). The next year - I was going to swap it out - and they quoted me a price of $585 to exchange the same T... I pointed out that was more than a 300 percent price increase in 12 months. The guy asked me to wait for a minute - and came back with a new price of $185 for the same T of He. Magic - but I made the sale quickly before they changed their mind!