Smart pots?

I have a few of these laying around from a few years ago, and was wondering if they might be beneficial for bonsai, or maybe pre bonsai. They are basically a bag made out of felt, I think.

They could be used as training pots instead of planting in the ground. The main reason for felt pots is for ease in taking from growing pot to landscape planting, the pot is usually cut off when the tree is planted. Generally they don't have much use in Bonsai. They might give better root development than plastic because they might allow for air through the pot.

Okay thanks. Maybe it'll be something that I just experiment with.