Bel-art f14650-0000 pmp 1532ml urbanti high-speed filter funnels, 2/pk unsurpassed for non-vacuum, high-speed filtration, these clear funnels have internal helicoid ribs to increase the filtration speed. Vertical outer ribs prevent airlock. Made from autoclavable polymethylpentene plastic, these funnels are glass-clear, unaffected by corrosive liquids, and are heat resistant to 177c (350f).