Introducing our high-quality 18mm screw for GC GCMS instrument clear headspace vial metal caps! As a trusted factory, we prioritize precision and durability in our products. These caps are specifically designed for headspace vials used in gas chromatography and gas chromatography-mass spectrometry instruments. Manufactured with utmost expertise, our caps ensure a secure and reliable seal, preserving sample integrity and preventing contamination. Join countless research laboratories and pharmaceutical companies who rely on our factory's exceptional products.