This PF strain is no different strain that the normal PF Classic. However this strain has been cultivated from approx. 1990 only on PF cakes (brf/verm) with no interruption of tissue culture.
In order to keep this strain clean we hope you only use them on brf/verm cakes as the PF style describes. Classic 90 prints are a kind of collectors items I think and that's how they are offered. In order to keep this strain 100% real we will place the returned 90 prints in the regular Classic stock.
This strain was donated by René of Perfect Fungi Europe. This strain is 100% Robert McPherson original. So it is the one and only PF Classic from the one and only Mister PF.

source - www.fsre.nl