2 PCS B-0230-K Wall Mount Faucet Installation Kit - for T&S B-0230 Style 1/2‘’ NPT Faucets Replacement Include 2 PCS 1/2" NPT Short Elbows, Nipples, Lock Nuts, Washers - Brass

As others have noted, the thread isn't exactly right for the faucet. Had to try 3 times, finally using a copious amount of Teflon tape to get these to seal and not leak. Why isn't someone making these with a true NPT thread?

I haven't run water through these yet, so I will update. However, just looking at the design, these are going to restrict water flow. The threaded fitting they put into it extends beyond the opposite hole, blocking water flow. Poor design....

The item consists of two 90 degree blocks with 1/2 inch female pipe threads on both sides. Short pipe nipples are included but their male threads are noticeably smaller than typical. The result is that the nipples bottom out in the body of the part, blocking most of the flow. The instructions suggest using plenty of tape or pipe dope, but these are a poor workaround for a properly fitted part.