Incabloc and Kif are the 2 vendors that supply most of the (escape wheel) shock absorption components for mechanical movements. Kif is generally considered to be inferior to Incabloc, and this has been the source of some debate since Rolex sources their shock components from Kif.
The component's function is a bit complicated, but, basically, the escape wheel (the tiny wheel containing the hairspring you see revolving back-and-forth in a mechanical watch) pivots on a central staff that is seated in between 2 jewels (used to reduce friction)
(this is a picture of an escape wheel removed from a movement (the jewels are not shown))
If the movement (watch) is dropped or suffers a sudden deceleration, the pivots, which are relatively delicate, can be bent, broken off or damaged. The shock absorber basically allows the pivots to 'float' a bit in an effort to absorb the shock and reduce damage to them. The tiny spring you see above the top jewel (the ruby colored part you see in the center of the following photo) returns the pivots to their neutral position after the shock subsides
(This is an Incabloc shock absorber)