With each other, these decide the full selection of movement, called the garage door opener travel limit options. trolley should stop inside the totally open up position at minimum amount 1 inch within the end bolt about the opener rail. Welcome to GarageDoorPedia.com, The final word portal for your garage https://youtu.be/wSkWTAdm-Gg?si=pR5EXdjVuNYjtHN7