The Series D-140 is designed for small volume injection into gas chromatographs. Since the sample is totally contained within the needle, it is totally displaced by the plunger. Any residual sample or variation in sample size are minimized. (This also means that each size syringe has a different needle design. When ordering extra needles, be careful to specify the correct one.)The PTFE seals, needle, plunger, and barrel are all replaceable. Thanks to superior alignment, the D-140 can be assembled time after time without difficulty or damage.