Our pine pellets are ENplus A1 certified, we use only barked spruce sawdust, while our mixed pellets are made of a mixture of pine and poplar sawdust of quality corresponding to A2, its ash content may be higher.   Basically, for a practical User, it is the quality the Manufacturer prescribes for his/her heater which is important. There is a significant difference, the ash content:   For quality A1 it is 0-0.70 m%;    For quality A2 it is 0.70 – 1.7 m%;