These 850 Ball Valves have NPS straight (aka parallel) threads at each end, and are designed to be fitted with straight thread thru-hull or pipe fittings.
Straight threads are not "self-sealing". You must use pipe joint compound, thread seal compounds, or "Teflon(R) tape" to seal the threads when making connections.
An advantage of parallel threads over tapered threads, however, is that there is maximum engagement between the mating threads providing an especially strong connection.