a high speed apparatus for pocketing documents in a pocket . a document to be pocketed is diverted from a document track towards a cupping apparatus by a pocket selector . the cupping apparatus includes an initial cupping rib and first , second , and third drive rollers , with a metal pinch roller being positioned opposite the second drive roller to cup a document to be pocketed . the leading edge of the cupped document encounters a document spring to create a &# 34 ; travelling wave &# 34 ; which functions to push the trailing edges of documents already pocketed away from an entry point to the pocket to enable the document to be pocketed to enter the pocket without collision and to enter in the right order . the document spring has a rectangular opening in each end thereof to enable the end to be secured to a rectangular boss located on a guide member within the apparatus to provide a quick change construction .