Abstract: A nozzle (10) with lateral slots (16, 17 and 18) for discharging a high pressure liquid for treating a work material (30) is described. The nozzle has a constriction orifice (15) between an enlarged or main orifice (13) and restriction orifice (14) leading to the slots which increases the velocity of the liquid issuing from the slots. The nozzle is particularly adapted for deburring transmission fluid channels in transmission main control valve bodies.