This Silca Thread On Schrader Chuck has a hose barb on one end and threads onto Schrader valves on the other. This comes from the same vendor who has supplied them exclusively for SILCA pumps for more than 25 years and makes a great replacement, or addition if you are buying a new Stainless Presta chuck or CP1 Disc Adapter for your older pump.

This part is made from nickel plated brass and uses on o-ring to seal to the valve.