R12 Pricing, and what is "12A"

[davepl]

After a long thread and helpful deciding on R12 vs R134, I was all set to make the decision to have my all-new-parts-but-stock AC system filled with R12, but it's $160 a pound, and we need about 4 pounds. With no guarantee that it won't leak, that's a pricey gamble.

I see "RED TEK 12A" for sale cheap on eBay (more like $14 a pound):

Amazon.com: RED TEK 12a Refrigerant 20 Lb...
But what the heck is 12A? Sounds like a name they made up, because it doesn't anywhere say that it's real 12.

That's a 10X price difference, so can someone educated me on the differences?

My system also already had the 134A connectors on it, so I think it may have had a conversion done in a previous life.

LMC said the reman compressor (stock style) is compatible with 134A. They didn't know anything about the oil inside or whether its compatible, but you'd assume it has to be if the compressor is listed as compatible...