The «VENT» marking on the screw cap indicates defined aeration. The clicked-in «VENT» position is clearly seen by means of a slightly raised rectangle found at the highest point on the cap. When the cap is turned clockwise 90° the flask is closed and gas-tight.

TPP filter screw caps feature a high-grade hydrophobic membrane with a pore size of 0.22 μm. We employ our own bonding process to join the filter to our plastic with optimal results.