Structural improvement of piston set for use in hydrant

An improved hydrant with comprising:

• a hydrant main body, wherein two sides of which are respectively formed with a water inlet pipe end for being connected to a water supplying pipeline, with preset locations defined at two water inlet pipe ends being respectively disposed with a water control bolt for adjusting water inlet amount;
• a front end of which is extended with a water outlet pipe end for being connected to a water dispensing pipeline;
• and a center of which is upwardly extended with a valve chamber for receiving a water control valve, which is composed of:
• a valve member, rubber pads at two sides of the valve member, inside which an integral piston set is disposed, a valve rod for operating the piston set, a cover, a valve cap, and a rotary button for locking and operating the valve rod, wherein the integral piston set is a composite of a piston rod and a composite piston cylinder with an integrally enclosed structure made up of a stainless steel base pipe and a plastic sleeve member covering an exterior of the stainless steel base pipe.