P2P constraint limits the translation so that the local pivot point of 2 rigid bodies match in worldspace. This can be useful to make chain.

Icon Size:
Defines size of the icon in the viewport.

Master Object:
Master object is base object of constraint. You can pick Dynamic / Static / Kinetic object for this. If you don’t use this option, objects constraint to this icon position.

Disable Collision:
When checked, disable collision between master object and constraint object.

Constraint Object:
You have to pick Dynamic Object for this.

Pick:
Select single object to add from viewport.

Add:
Select multiple objects to add from scene explorer.

Remove:
Remove selected objects from the list.

Breakable:
When checked, constraint breaks when objects get some impulse.

Impulse:
Defines breakable impulse threshold. If object get impulse larger than this, constraint breaks.