This is a very good utility hat Unity has, and it's really useful to make softbodies or springs. Press flag again to apply values if you change them.
UPDATES: -0: Maybe later I do a change that makes it to return to a fixed rotation. Also I planned to add some resistance on some distance and some breaking force (to be able to break the joint at some point). -1: I added a breaking force. Now the joint breaks if it is stretched too much. -2: I added some resistance on a determined distance. -3: I made a better resistance and tried to introduce the joint direction, but it still doesn't work quite well. -4: I invented a way to make it work and added also to that rotation the smoothness, stretchability and resistance. -5: I saw tat there still was missing something, so I added a complete stop distance and the ability to collide with the jointed object. -6: I added a line to represent the joint,and made it be more red the closer the joint is to break.