Summary Replacement pool jet for swimming pool. Threads are modeled using the National standard taper pipe threads chart but modified for better printing and application needs. IE its not meant to make a watertight seal. The pool jets available in my local pool store have a 1.5"NPT to 2" threaded body with a 2" cap. This design is meant to eliminate the cap and keep a low (slim diameter) profile to accommodate the lack of clearance in our pool.