A packaging cushion assembly includes at least one foldable packaging plate including a base plate that has two opposite first sides, two opposite second sides, two opposite first side plates connected respectively and foldably to the first sides, and two opposite second side plates connected respectively and foldably to the second sides. The tool includes a tension mechanism and a ball set and cut-off mechanism. These labeling reagents are useful for labeling probes or targets, including nucleic acids and proteins.