BD PosiFlush™ Prefilled Heparin Lock Flush Syringe is available in two concentrations—10 USP units per mL and 100 USP units per mL—in 3mL and 5mL syringe sizes and fill volumes to help support your catheter maintenance practice. It may help maintain catheter patency by locking vascular access devices, when used in accordance with your institution access maintenance protocol.