Inserts fit standard-mouth 1.8 ml, 12 x 32 mm vials, and are placed directly in the host vial. Inserts measure 5 x 31 mm, except for TriSpring inserts which have a length of 29 mm. Flat-bottom inserts have the largest capacity. Tapered-bottom inserts allow sampling of just microliters of liquid, with nearly complete withdrawal from the tip. Tapered-bottom inserts are available with either flame-drawn pulled points, or form-shaped mandrel points. TriSpring Inserts - These inserts have a plastic spring attached to the tapered bottom, which centers the insert in the host vial and adsorbs shocks if the insert is touched by the autosampler needle.