Avantor offers Kjeldahl flasks that feature round bottoms and long necks. Borosilicate glass construction and controlled wall thickness provide maximum chemical resistance while maintaining thermal shock protection. Flasks offer standard taper top joints. Select unfinished necks, tooled necks for tight stopper fit and breakage protection, or a threaded top style. A variety of capacities are offered, including micro models, and some options meet ASTM specifications. Kjeldahl flasks are offered by the case or in packs.