which causes air to get pushed and sometimes creates a low popping sound.
id say it is a pretty essential tool if you plan to do vocal recording,
you can save yourself some cash by making your own,
with a pair of tights and a coat hanger,(or wherever your imagination leads you)
just bend the wire coat hanger into a 6" circle and stretch the stocking over it, then place it about 3 to 4" infront of your mic :)
