If your sliding glass door has started making that awful grinding noise or just doesn't move smoothly anymore, these replacement rollers will probably fix it. They're the DR-135 model with 1-1/4 inch steel wheels that have precision bearings - which basically means they roll quietly and smoothly without all the resistance. The stainless steel construction holds up well against rust and wear, so you're not doing this repair again in six months. They measure about 1-11/16 inches long by 1-1/16 inches high, which is the standard size for a lot of sliding patio doors. Installation is pretty straightforward if you're moderately handy - usually just lifting the door out of the track, replacing the old rollers with these, and putting it back together. The difference in how the door moves is immediate - no more sticking, no more loud scraping sounds, just smooth quiet operation. It's one of those home maintenance tasks that seems intimidating but is actually pretty simple, and makes your door feel brand new again. Much cheaper than replacing the whole door system, that's for sure.