These borosilicate glass heavy wall filtering flasks can be used with FILTERWARE Filtration Apparatus (LG-1755). Supplied with a silicone stopper with 9/16" hole and a #2 hose connection, the 1000mL flask has a 3/8" hose connection, whereas the 2000mL and 4000mL flasks have 1/2" connections. Limited 90-day warranty included. Research, industrial and healthcare professionals rely on SP Scienceware for their sample handling needs. Sold worldwide, Wilmad-LabGlass brand laboratory glassware features over 7000 items including NMR and EPR consumables and specialty glassware, as well as custom fabrication for individual glassware, glass repair services and OEM glass parts. Bel-Art and H-B Instrument brand laboratory supplies complements Wilmad-LabGlass with over 5,000 items from safety wash bottles to fume hoods, thermometers, racks, desiccators, hydrometers, ice buckets, scoops and spoons.