Whirlpool 4392892 29-Inch to 77-Inch in the Wall Vent Periscope
This item is designed to fit between the studs inside the wall. It does a great job of carrying the exhaust air through the top plate and into attic/floor space. You should use the 4" aluminum vent to complete the run to the outside. This dryer vent rough-in system has (3) 2-1/2" clearance telescoping sections that extend from 29" to 77". It also has one male snap-lock fitting, one female snap-lock collar and mounting strap, as well as all-metal rigid construction that meets most in-wall codes.