Nozzle jet block is designed to thread the -3 thread side of the nozzle jet into the block. RBS has two that are threaded and two that need to have the threads tapped into the block but holes are drilled. Threads are 3/8-24.
Note: This is a used item. This item might have been taken in on a trade. RBS may have inspected this item and deemed re-usable. There is no warranty expressed or implied with this item.