Check out this video of Neal Pultz, Pultz Poppers, explaining why he uses balsa wood for his poppers.  The popper shown here is the Peck’s Popper black, red, black, 1/0 by Pultz Poppers.  Check out all of the poppers made by Pultz at

Peck’s Popper Black, Red, Black 1/0 by Pultz