Received on time as promised. I decided to install them the same day. No instructions, but Youtube fixed that. Because the old lifter were so warn out, I had to hold up the window with my head when I removed the first one. The removal and re-installation took less than a minute, so no headache. Once the first new one was installed, it held the window up so I didn't have to hold up the window to replace the second one. Once both lifters were installed, the window operated better than new. The window opened, lets call it briskly, with a smoothness I haven't seen in years. Closing the window was stiff, but they are new. A great replacement for the cost.