Cokin P holder Nuetral Density.

I'm looking for a multi-stop 3 or more actually ND filter for a P series holder.

The 155 and 156 appear to be A and Z series holders only tho....

Can P filters be used in a Z holder? I'd hate to have to upgrade to Z and have to replace all my P filters...

Do Lee filters fit in the P holder?

Based on Cokin's website ( http://www.cokin.com/i​co15/ico15-haut.html ), the P series uses a 84mm square filter. The Z-Pro uses a 100mm square filter so no, Z-Pro filters won't work for you. If I understand your question...you are looking for ND filters for your Cokin P-series holder? B & H has Cokin filters 152 (1 stop), 153 (2 Stop) and 154 (3 Stop) that are designed for the P Series.

I used to have the P Series but recently changed to the Z-Pro since there are more options available (plus I can use wider lenses). Good Luck!

can you use other filter brands in your Z holder?

I see the 154 3-stop but I was hoping for something like 6 or 9 stop in a resin filter but I doubt I'll find that...

although I could just stack multiples no?

Since the Z-Pro uses 100mm square filters, it is compatible with other brands as well (like Lee Filters) therefore you have more options. And yes, you can stack multiple filters...