Bottle Top Dispenser Fortuna POLYFIX 50ml w/coated PTFE Piston POLYFIX® Dispenser comes with 2 adaptors made of Polypropylene GL 40 and 45. Robust: POLYFIX® Dispenser with PTFE-coated glass piston For several dispensing tasks (for example, when dispensing of crystallizing media) the PTFE-coating of the glass piston is very useful. For weak acids and alkalis we recommended the POLYFIX® Dispenser