Product review (5 stars): Whirlpool 4396006RW Venting Close Elbow
The Whirlpool 4396006RW Venting Close Elbow is a very simple item.  It is constructed of aluminum and is very easy to install with a couple of 4 1/2" hose clamps.  It allows you to set your dryer as close to the wall as you are going to get it.  It also allows my dryer vent hose a straight shot to the through-the-wall dryer vent without any bends or crimps.  That's got to be a good thing.  Thumbs up!!!