This is a set of six Castle Creations 4mm Bullet Connectors.  The package contains a total of 3 male and 3 female connectors. 

If you want something done right, you usually have to do ityourself. Castle Creations was never totally satisfied with the optionsfor bullet connectors for high power applications, so they designed andmanufactured their own. Castle Creations Bullets make a perfectconnection, every time. Simple as that. Available in a lovely shade ofgold and made in three sizes: 4mm, 5.5mm, and 6.5mm.