These borosilicate glass cylindrical reaction vessels are without constriction at the top and have a flat bottom. They feature sturdy walls and a tooled flat flange with a surface ground to assure a tight seal. There is a gently sloping contour at junction of side wall and bottom, thus preventing any weakening that might occur with a sharp shoulder. LG-8080 vessels use LG-7316-106 clamp; LG-8082 vessels use LG-7316-108 clamp.