This tool is used with crimp-type bullet-style connectors (sold separately). This crimping tool has a hexagonal jaw which provides an even crimp all the way around the connector to firmly lock the wire in place. This is also a ratcheting style crimping tool, so it is easier on the hands.

Crimp on bullets available here: 16g or 18g
Usually mated within sleeves, available here: single sleeve or double sleeve

Note: This will NOT work with original solder-type bullet connectors.