Creating Physics 2D Extensions components
Physics 2D Extensions adds a number of new components to Unity. You can find all of them under Component > Physics 2D > Extended Joints, Component > Physics 2D > Controllers, and Component > Physics 2D > Other.
Extended joints work like Unity's physics joints - they provide a constraint of motion between two rigidbodies. These components should be placed on one of the two rigidbodies they affect. Joints can also be fixed to the world by not providing a second body. Extended joints have break points, break events, and automatic anchoring.
Controllers apply a set of constraints to an entire group of rigidbodies, and only affect a certain area. Controllers can be added to objects with or without rigidbodies. They are used to represent forces like wind and buoyancy.
The Controller Filter is a component that allows more fine-grained control over whether a body will be affected by a controller. This component requires a Rigidbody2D to be present.
A Drag Control component is included, for dragging rigidbodies around with mouse or touch input.