PP. With NS stopper made of PP. Tolerances class B acc. to DIN EN ISO 1042. Translucent, with ring mark individually calibrated to 'In'. Thermal stress up to 60 °C does not permanently exceed the tolerance limits. To preserve markings, cleaning at no higher than 60 °C is recommended. PP. With NS stopper made of PP. Tolerances class B acc. to DIN EN ISO 1042. Translucent, with ring mark individually calibrated to 'In'. Thermal stress up to 60 °C does not permanently exceed the tolerance limits. To preserve markings, cleaning at no higher than 60 °C is recommended.