They work well. I have used mine to replace brakes,bearings ect. on my 34' gooseneck trailer. Luckily have not had to use it on the road yet!
Update: Should have never said that I have not used on the road yet!
Changed a flat tire on my gooseneck trailer in 102 Degree Heat last summer just 40 miles into a 2200 mile trip. Trailer scaled at 14K on double axle trailer and trailer aid worked flawlessly.!!