Original: A vacuum tight seal and stability of the BÃ 1\/4 chner flask and filter are essential during the filtration process. A BÃ 1\/4 chner ring can be used with BÃ 1\/4 chner funnels, flasks, glass crucibles and gooch crucibles.
Simplified: Attached to the hole in the side there is a vacuum which sucks the air out of the BÃ 1\/4 chner flask.