AC oil filters and anti-drain back valves?

[2QUIK6]

A guy at the auto store was saying that some regular AC oil filters have the anti-drain back valve while others don't. Anyone know how to tell and if the regular PF52 and PF1218 do?
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Also, do all of the AC Ultraguard Gold filters have the anti-drain back valve? (That is if you can find them anywhere anymore..I was under the impression they did and had been using them but can't find them anymore.)

 

[REDS HOT AIR]

you can see the black flapper in the small outter holes if it has one

just blow in the middle hole of the filter to check that it seals properly ......you shouldnt be able to blow thru it at all.


im finding that the ac filters start to drain down after only short usage so im switching back to fram