cstreu1026 once bubbled...
back when I was shopping for regs, I was told that the Z1 can be had in an environmentally sealed version. I think that would be first choice though the M1 is tempting.
I believe you mean the T1 (which would be the T1x if environmentally sealed). I don't believe either the Z1 or B1 can be env sealed. The M1 and T1x are.