Parveen manufactures both positive (fixed orifice) and adjustable choke in pressure rating from 2000 PSI to 15,000 PSI. Adjustable Chokes generally have an externally controlled variable area orifice with a visual mechanism to indicate orifice size in 1/64" increment. Area of the orifice can be varied to vary the flow rate by rotating a handwheel which imparts linear motion to the stem integral with hand wheel. Positive Chokes accommod-ate replaceable parts having fixed orifice dimensions.