Diamond SureFlow Bottle Top Dispensers have been designed with several features to make the dispensing of your valuable laboratory reagents easier than ever. With your choice of standard or recirculating models, features include a unique piston design which allows cleaning and servicing without changing the calibration, and a springless valve which requires less maintenance, offers higher reliability and added chemical resistance. Dual graduations, volume lock and four additional bottle thread adapters are all standard. Recirculating models help eliminate the loss of your valuable reagents by priming without loss.