Free sample amber vials with caps supplier for HPLC and GC Standard Screw Thread HPLC Vials: Screw thread caps and vials are often used in conjunction with Shimadzu, Spectra-Physics, Varian, and other autosamplers; Vials are manufactured of Clear, Type 1 Class A or Amber, Type 1 Class B borosilicate glass and include a write-on patch for sample identification