Blue Anodized Aluminum Adapter (AN 932), Inch Male NPT Allen Head Plug

For tight-access ports, the Allen head drive is the big advantage on this plug. You can install and remove it with a standard hex tool without needing room for an external wrench, which is why it is commonly used as a port-closing plug in hydraulic circuits and fluid power assemblies.

It’s made to fit any standard NPT port of the correct size. Just make sure you're not over-tightening it during installation.

Tight spots are exactly where that allen head design earns its keep. A hex wrench or allen key sits flush and low-profile, so you can get torque on the plug without needing the clearance a standard bolt-head wrench requires. If you've got a recessed port or something with surrounding hardware crowding it, this style typically gives you a lot more room to work than a conventional head would.