Extends the burning time by increasing the fuel capacity:
On the P38+ Pellet Stove it increases from 50lbs to 110lbs
On the P43 Pellet Stove it increases from 50lbs to 110lbs
On the P61A Pellet Stove it increases from 72lbs to 132lbs
On the P68 Pellet Stove it increases from 78lbs to 136lbs
On the PC45 Cereal/Pellet Stove it increases from 72lbs to 132lbs

FYI - A bag of wood pellets weights 40lbs and produces +/- 320,000 Btu
Wood pellets are bought by the 40lb bag, a pallet typically has 60 bags.