This is a replacement wheel for a sliding screen door. As you can see from the picture, mine was quite worn out and ready to be replaced.It's very simple, I've broken the wheel into two parts to make it easy to print. There is no need to glue the two parts together since the bracket it mounts to already holds it together, but it won't hurt if you glued it either. Once printed, the two parts of the wheel should fit together and look more or less like the original. To get the screen door off, there should be two screws sticking out from both the top and bottom of the screen door. These screws tighten the wheels onto their tracks and also holds the door in place. If you loosen these, you'll be able to just lift the door off its tracks and pull it out. To get the original wheel off the mounting bracket, just take a flat head screwdriver and wedge it between the bracket and one side of the wheel. Add a little twist and the main axle should pop out of that side. Do this to both sides and you should be able to pull the old wheel off.