Woulfe bottles, Erlenmeyer shape made of borosilicate glass 3.3 (5000 ml bottle), thick walls, for jobs using vacuum, with plastic coating as splinter and implosion protection, glass insert with screw-off plastic hose connections (PP), intermediate piece with vent valve, pressure gauge with 2 scales (1000 to 0 mbar, 760 to 0 mm Hg). Also available with non-return valve at the side.