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I like the idea of being able to shut off my air sources without double tanks but dont want to spend the money on a whole valve would one of the h attachments work on a regular k valve

No it will not work.  You will quickly find that spending money and scuba diving go hand in hand.

The Diverite "H" adapter alone lists for $80. There is a complete OMS H valve on the Milwaukee Craigslist.
                                                                                       I would have bought it myself if I didn't despise the company.

yea i know it
im still in school and working full time just to pay for my dive gear and motorcycle so i like the one on craigslists but if i buy that in time would the dive rite adapter work or not

That OMS H-Valve that Matt linked to is a complete H and doesn't need any adapters.  I think that OMS valve has the surface O-ring and not the barrel style that everyone, including Dive Rite, has gone to now. 

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  I think that OMS valve has the surface O-ring and not the barrel style that everyone, including Dive Rite, has gone to now. 
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Yeah, on second thought you'd better not buy it. It may kill you  ;D.

Also I belive that steel tanks are 3/4 inch threads wihil aluminun tanks are 7/8 inch.  Its late an I could be wrong!  Just make sure of the tread size for the tank you want to put it on!
Jeff

Some of the older steel tanks have different size valves.  They are all the same now.

That is correct, 3/4 is the standard now. Older high pressure steel tanks have a 7/8 (which is actually smaller than the 3/4") necks.