Adjustable tension plungers are preferred over the conventional plungers for gas handling. The adjustable tension plungers allow you to adjust the tension between the plunger and the glass barrel. Without a liquid the lubricate the seal, the movement of a conventional plunger may be overly stiff. The tension is simply adjusted by turning a knob at the end of the plunger.
The removable needle syringes are marked as series 19925. A variety of replacement needles are available for these syringes. These can be used to change the type of needle on the syringe or to replace a plugged or bent needle.
The fixed needle syringes are marked as series 19930. In these syringes the needles is permanently cemented into the syringe and it cannot be replaced.