Even if the door knob was turned it was in a state not returning so purchase for replacement. Originally it was not a lever, but since I arrived at the wall, I changed to a lever. Because the spring is solid, the feeling of use is pretty good. Although the rotation angle is wide due to the latch specification, I do not feel a problem in particular. I plan to purchase another knob room knob replacement when it becomes necessary.
Because the door knob has become difficult to turn, purchased to make it a lever type. Although it was easy to replace and install it, the operation angle for unlocking the latch was about 50 degrees and it was not possible to improve the ease of operation which was the change purpose. I think that the product of the door sliding lock has few options, but as a product specification it is helpful if there is description of the latch unlock angle.