This is one of the "newest" connectors to come out of China, it's being used now on a lot of the higher-capacity, higher current output Li-Po batteries. The brass bullet connectors are larger, (4.0mm) and longer than the EC3, and are rated for higher current loads.
These connectors are different from any of the other battery connectors we typically use in R/C models, so you must take care when using and installing them on your battery or ESC. One major difference is that the plastic part of this connector has no "male" or "female" half, both sides are identical. In addition, the brass bullet connectors will snap into either side of the red plastic part, so you must be careful when assembling this connector to make certain that you get it put together correctly to match any other connectors you may be using, especially if you are making a connection to mate with a Li-Po battery. And finally, the brass parts snap into the red plastic pieces from the FRONT, not from the back like most of the other connectors of this type, so you must slide the wires into the plastic pieces BEFORE you solder them to the brass parts. I have seen batteries coming from China (especailly those sold by HobbyKing) that have these connectors installed in a couple of different ways, some with the male brass bullets on the red (Positive) wire, and some with it on the black (Negative) wire. The parts of this connector are not marked as to gender or polarity, so if you are making a connector to match up to a battery, I suggest you have the battery in hand as you make it, so you can make sure you get the polarity correct and get the male/female bullet connectors installed so they will mate up correctly. Sold in pairs, enough to make one set of male/female connectors.
NOTE: It is the responsibility of the purchaser to ensure the correct polarity of any adapter or connector. Take note of the polarity of both the battery’s connector and any adapter you use to ensure that the red (+) and black (-) wires on the battery match the output side of the adapter. Incorrect polarity may cause damage to your battery and/or other device.
4.0mm Red Battery/ESC Connector
Weight: X grams