When it is necessary to splice in an extra length of tubing in your model's pneumatic system, this plastic part is very handy.

To ease the task of inserting this fitting (and others) into the tubing, first stretch the freshly razor cut end of the tubing with a pointed tool such as this 3mm diameter Philips screwdriver.  Any similar tool will do if it has a 3mm shank.  A bit of saliva will assist.

#PA-SR-0038  (4 pack)
$5.00