Gee, I think I took part in that discussion on the other forum so I guess I will weigh in here as well. The 2 by 4 test may be the only one prescribed by law but doing only that test is only doing half the job. The 2 by 4 only tests the travel distance under power to assure that the door will reverse if it encounters a low obstruction. The other half of the job is testing the amount of force the door exerts when an obstruction is encountered before backing off. As the article pointed out, there is no standard recognized test for that but there is a standard recognized adjustment method in the owners manual of each and every model out there that requires field adjustment. The model building codes require that the manufactureââ¬â¢s installation instructions be explicitly followed when installing any kind of Listed appliance or device and the manufacturer spells out the proper way to make these adjustments in their installation instruction. Thereââ¬â¢s the ââ¬Ålegalââ¬