4-leaf Barndoor for OCF Flash Heads from Profoto is a useful light-shaping tool made of durable glass fiber composite that allows you to direct the B2 Off-Camera Flash Head's beam onto areas that you want to light, and keep it from areas that you don't. The rotatable barndoor is also compatible with the B1 Off-Camera Flash Head and can be used in conjunction with the B2's OCF grid set.