Before I knew this product, I was exchanging every knob, but the interior door could be purchased at the home center but as for the external door, because the standards are different, the lever type can not be purchased, so I thought about remodeling When I searched on the net before that, I purchased it as it was as it was in my head. I was very pleased that the senior citizen made a lever style where I could not turn round knobs. Although it seems there is a form which is difficult to fix and hold depending on the shape of the knob, it is currently being used and looking at the state. If it becomes fixing failure, I will try to partially screw it. The installation was easy and the idea expanded. Thank you very much.