A US Airliner had to be diverted when two passengers got into an argument. The product Knee Defender caused this altercation. According to BBC's report, a passenger fought with another passenger because the latter attached the Knee Defender to his seat. Knee Defenders are attached to the front seat, preventing it from reclining. Reportedly, the passengers involved in the fight were travelling in Economy Plus class.

For those who are not aware about the Knee Defender, here are the few things to know about the product:

1. A Knee Defender is a pocket size device that helps in defining the legroom of a passenger in the plane. They are more like plastic clips and are much popular with tall people. The device costs US$ 27.41.

2. The Knee Defender limits the reclining angle of the seat. There is a pair of Knee Defender, and each is fixed on each arm of the tray table and stays fixed against the back of the front seat.

3. According to the product's website, the Knee Defender lets the person work, uninterruptedly, on his or her laptop. Moreover, it can also help the person suffering from deep vein thrombosis, which may develop due to limited leg space.

4. The Knee Defender comes with a courtesy card. It can be given to the co-passenger sitting in the front, informing him about the limit of his seat's recline angle.

The courtsey card says "I am using Knee Defender. Knee Defender is a small plastic device that helps me protect myself by limiting how much the seat in front of me can recline. I wanted to let you know about this and provide the following information," according to the official website.

5. Most of the major airlines in the U.S. have banned the product. However, there are still a few airlines who alllow their passengers to use Knee Defender.

6. Ira Goldman has designed Knee Defender, according to Straitstimes.