This system will count seed flow on up to 24 rows. I was had this setup on a box drill to tell me when I ran out of seed or a chain came off. The harness will fit a 40' 3 section box drill or anything smaller than that. The monitor, 6 hi flow sensors, and all cabling come with it. I also used it to drill soybeans.
Here is the link to the monitor.
http://www.sensor-1.com/product_p/pm2005.htm
Everything worked when I last used it.