Large Door Guide with Roller

This is a good door guide if you do want to, or can't make the groove in the base of the door, for the other door guides, or for larger doors that might need a bit more guidance to keep against the wall. Can be adjustable for up to a 70mm door.

This can be used on an exterior door as well.  

The advantage with a door guide with wheels is you can use more than one, and they are not going to jam, as they will with the groove in the bottom of the door. 

120mm long and 50mm wide. Wheel is 50mm in diameter. Comes with screws.