Complete, two-piece, Prong Fasteners include a prong base and compressor. They are ideal to use in file folders that need to be modified or added to frequently. Locking compressors slide over base prongs to keep papers tightly compressed to save valuable filing and storage space. Both bases and compressors are made of brightly finished, corrosion-resistant, tempered steel.Complete, two-piece, Prong Fasteners include a prong base and compressor. They are ideal to use in file folders that need to be modified or added to frequently. Locking compressors slide over base prongs to keep papers tightly compressed to save valuable filing and storage space. Both bases and compressors are made of brightly finished, corrosion-resistant, tempered steel.