This schlenk tube is with an outer ground joint on Top ,a high vacuum valve at side which can be used to exchange the atmosphere of the flask is to flush the flask out with an inert gas.and the Counter flow or sampling operations can easily be made by purging through the sidearm and removing the plug. These are great for storage or for running small reactions.
Laboy glass flasks are heavy wall designed,made by hand-blowing to ensure uniform wall thickness, made of high-quality borosilicate glass and annealed at 800 degree Celsius ,can be heated directly in an open flame and can withstand typical laboratory thermal variations in Chemistry processes like heating and cooling.