Some grunt calls also have different settings on their calls where You move the rubber O-rings to different notches on the plastic piece below the reed for Mature Buck,Young Buck,Doe or Doe in Estrous...other calls have the flexible black tube at the end of the caller where You can leave it in close to the tube or stretch it out-ward to make a deeper grunting sound.
Most Companies that sell the Gurnt Tubes have a small disc that goes along with it so You can practice and get good on sounding like a Buck or Doe!Then there's the Snort-Wheeze Calls that get the attention of a Buck that might have strayed away from You and casues it to come bacl for a Challenge/Fight.....some times it can work against You and scare a Deer off so timing is of essence and doing it right can make a big difference.I also like to do a little light rattling when the Bucks are sparring or during the Rut when it can also help You draw a nice Buck in close for a shot!