Easily provides full backflow and backsiphonage backflow protection. The amount depending on each particular installation.

• Provides an in-line air gap, usually installed in the last 5 feet (1.5
  meters) of the indirect drain piping and must be in the down leg of the drain
  line piping.
  
• Unit can be tilted at any angle (down as low as 45 angle) when installing
  if needed, (window opening on top side).
  
• Molded clamp groove plus included "Jiffy Clip" enable easy vertical wall
  mounting as noted in top 2 figures.
  
• Unique design incorporates a rotatable splash guard/splatter shield, to
  eliminate splatter of water droplets out of either air gap opening.
  
• Unit approximately 8" (20.32 cm) long.
  
• Unit design lab tested at 15 G.P.M. (56.8 Liters/minute). Recommended usage
  is 1 to 7 G.P.M. (3.7 to 26.5 Liters/minute).
  
• All noted threads are American NPT threads.
  
• Multiple air gap openings far exceed the code mandated minimum of (1)"
  vertical.
• NSF and UPC Listed