Abstract: An apparatus for defining a tunnel through a wall includes a first elongated tubular section having an outboard end and a distal end. A first peripheral flange extends around at least a portion of the periphery of the outboard end of the first elongated tubular section. A second elongated tubular section has an outboard end and a distal end. A second peripheral flange extends around at least a portion of the periphery of the outboard end of the second elongated tubular section. The cross-sectional shape and dimensions of the second elongated tubular section are sized to slidingly telescope within the first tubular section when the distal end of the first tubular section is inserted through a hole in a first side of a wall and the distal end of the second tubular section is inserted through a coaxial hole in the opposing side of the wall.