Jet Subs Crossover Jetting Bull Nose and Crossover Jetting Subs are manufactured from AISI 4145. Flow is expended on the wellbore through numerous high velocity hard faced nozzles. The nozzles in the bull nose are typically angled. The nozzles in the jetting sub can be angled or straight depending on the customer's requirement. Crossover offers various nozzle sizes and number of ports.