The ergonomically shaped stoppers are suitable for closing volumetric flasks, mixing cylinders and standing bottles.– Complies with DIN 12254 – Ergonomic polyethylene stopper for easy and safe tightening or removal – Taper with several grooves ensures optimal flask sealing – Coloured inserts in the different sizes of stoppers allow the easy identification of the corresponding standard ground neck size – The colour identification system used for the inserts is identical to that used for the Keck™ interchangeable glassware clips – The batch indicator represents the production period (year and month) – With material designation for polyethylene "PE04" on the underside of the product The ergonomically shaped stoppers are suitable for closing volumetric flasks, mixing cylinders and standing bottles.– Complies with DIN 12254 – Ergonomic polyethylene stopper for easy and safe tightening or removal – Taper with several grooves ensures optimal flask sealing – Coloured inserts in the different sizes of stoppers allow the easy identification of the corresponding standard ground neck size – The colour identification system used for the inserts is identical to that used for the Keck™ interchangeable glassware clips – The batch indicator represents the production period (year and month) – With material designation for polyethylene "PE04" on the underside of the product