Filter circles. Binder-free glass fibre filter which offers medium particle retention, high flow rate and good loading capacity. Used for high efficiency laboratory filtration as well as air sampling. Stable up to 500 °C. - Filtration speed: 12 s. - Thickness: 0.3 mm. - Weight: 55 g / m². Filter circles. Binder-free glass fibre filter which offers medium particle retention, high flow rate and good loading capacity. Used for high efficiency laboratory filtration as well as air sampling. Stable up to 500 °C. - Filtration speed: 12 s. - Thickness: 0.3 mm. - Weight: 55 g / m².