This inexpensive portable titration set features a 2mm straight stopcock with PTFE plug. The borosilicate glass buret is filled by pressure supplied by the rubber bulb. A small hole in the filling tube at the "O" line permits setting of the liquid level and excess titrant is returned to the bottle. Complete Set furnished with buret, bottle (LG-4230-120 or LG-4230-124), rubber hose, rubber stopper (LG-10392-126 or LG-10392-130), and rubber bulb (LG-4340-100). Accessories: Vent Tube (LG-4230-130)