Very comparable to the type you find in big box stores - and I suspect should last equally as long. For those who ever replaced these before, you may be wondering how to get the door off when it rides on rails. The lower screw is the adjuster, before trying to remove your door, turn the lower screw counter-clockwise to "lower" the door by "raising" the wheels into the frame. This will give you just enough gap to pull up on the door and off the lower rail. Then it's a matter of pivoting and hoisting the door out. If you're of smaller stature, use the buddy system. I managed to wrestle the bear out myself. Removing the old ones is as simple as pry-barring them out once you take the upper screw out that holds it to your frame. It may take a little work to get them out from years of neglect and corrosion, but they come out. Installing the new ones is as simple as tapping them into the door with a small ball-peen hammer and punch. Be gentle with the new ones, they don't need a lot to get them in. Then ... as cliche as it is, installation is reverse of removal. Be sure to turn the bottom screws counter-clockwise on the new ones to "bottom" out the new wheels, or do this before installing them into the door. Once you wrestle the door back into place, have somebody hold up that corner of the door, and turn the lower screw clockwise until all the slack is taken out. By lifting the door, you don't fight the weight of it setting the wheel height. Then repeat for the other one. This job required me to drill a larger hole for this mounting screw, and it appears all the newer ones out there use this larger one too (I have an older door). Start to finish, you can replace these in less than 20 minutes. Be prepared though ... use 1 finger to open or close the door after you replace these! You'll be surprised how smooth and effortless the new bearings will behave and how wore out your old ones were. I nearly broke the glass slamming the door using my usual level of force to pull it closed ... huge mistake. It went from 0 to 60 in about a thousandth of a second and slammed into the frame. oops... learn from my mistakes ;)