I know for a fact what they are.... Way back a NASDS store in Riverside Ca Distributed them in the office was above the scuba shop-- Z-90 use to put out masks and snorkels as well---They have not been made in Years--- There are no parts for them--- I know because I used to work at the shop after they went belly up---We had boxes of crap left over for years I think Wayne Miller still has 1000's of snorkels and Diaphrams for the purge masks... We used the Z-90 seconds stages on some of our rental crap gear... I hope you dont try to use that Reg--- we used to use them to show customers what not to use underwater...those were the days, now the shop is gone...
