This inside door handle retainer is the horseshoe shaped clip that slides in behind the handle and the window crank to hold them in place. You are buying a pack of 4
The window regulator and the door handle remote both have a groove made into their shafts and when the handle or crank is pressed onto the splined shaft, the clip retracts into that groove and thus stops the handle or crank from being pushed off by the cone shaped spring found between the handle and the door panel. This cone shaped spring is sold separately in a different listing.
For information sake these are the “large” version used on 1949 and older GM vehicles. In a different listing I offer the same clip but smaller for 1948 and older vehicles.