.A membrane intended for highly sensitive rapid diagnostic assays provides consistency and high surface quality. Unbacked Hi-Flow Plus 180 has a powder-free surface that prevents interference, making it suitable for infectious-disease testing, drug testing, and cardiac-marker diagnostic test kits. Hi-Flow Plus 180 provides a nominal flow rate of 180 seconds across 4 cm of membrane, a flow rate variance of 25%, and a thickness variance of 10%. A master roll average specification of ±11% for capillarity and ±6% for thickness ensures membrane consistency. The membrane, manufactured by Millipore (Cork, Ireland; 800/645-5476), compliments the company's other existing Hi-Flow Plus membranes. The backed membranes provide lateral flow rates of 65, 75, 90, 120, 135, 180, and 240 seconds across 4 cm of membrane. A clear polyester material increases tensile strength.