Featuring a center neck and two side necks with full length outer Standard Taper joints that are 180° apart, these borosilicate glass reaction vessel lids have a conical flange

The bottom part of lid is finely ground for a leak-proof fit with flask. ML-1285's flange I.D. is 2" and can be used with flasks ML-1281 through ML-1284. LG-8030 is used on cylindrical or spherical reaction vessels with a 4" I.D. flange.