Smiths Medical ASD Breathing Filter 44mL Dead Space, Weight: 32g, Filtration Efficiency: ó99.9%, Connections: 15mm I.D. x 22mm O.D. on patient end; 22mm I.D. on circuit end. Method of Filtration: Electrostatic attraction, torturous path, depth, Med. All filters have ISO standard tapered ends to assure a consistent leak-free seal. All Portex filters are latex-free.