The vertical config is kind of the standard for homebrewing and that's why we offer it. The horizontal is our solution to a problem. The vertical coupler config has the top thermometer coupler 6" from the bottom. Now if you're to buy a 15gal kettle that means you would need approx 5 gallons of liquid in the kettle until it reached the thermometer. If you wanted to do a 5 gallon batch in a 15 gallon kettle the thermometer may not be submerged. The horizontal configuration keeps the thermometer submerged at all times.