Knee Defender sales have been through the roof following an altercation between two passengers on a United Airlines (UAL) flight.

The argument between the passengers caused the pilot to make an unscheduled landing. The Knee Defender is a gadget that uses two U-shaped clips to prevent seats from reclining.

The device’s website crashed today after news of the United altercation and sales went up. The Knee Defender sells for $21.95 and it was invented by Ira Goldman.

Most major airlines including United have banned the use of Knee Defender.

UAL stock is up about 0.4% Wednesday afternoon.