To be honest, this is not something that i have the resources to check,,namely bsbs. As to thier use,, i can put stuff in them as if a normal bsb. I think i got it,,, it has something to do with the cave tile edges,,,if i walk up to a cave wall ( reinforced or not ),,, i can drop as many bsbs (planted or not) as i can carry. I can drop them one at a time or all at once.