Precision all-glass construction virtually eliminates sidebands. Superior to PTfE inserts in variable-temperature experiments. Upper section of insert fits snugly into the outer NMR tube 2 mm O.D. insert stem is held straight within 0.013 mm. Use inserts with 5 mm O.D. x 7 in. L thin-wall NMR tubes only. Each insert supplied with a closing cap.Coaxial inserts are applied in external referencing and locking studying molecular interactions and determining magnetic susceptibility.Outer tube must be ordered separately based on magnetic field strength.