A Jetted Sub is used for clean outs, scale removal and other operations where a jetting operation is required. They are usually built with a Box thread up and a Solid Bull Nose down to run at the bottom of the string. If the jetting operation needs to be performed at the top of the string for any reason, they can be built Box up x Pin down as well.
A series of angled holes are drilled thru the side of the sub and carbide jets are installed. The pattern, angle and quantity of the holes is usually determined by the customer.