6.3mm block connectors are widely used in the automotive industry. They are often found on motorcycles where a higher current will be used that a 2.8mm mini block connector could be overwhelmed by. They are frequently used on the alternator/dynamo circuits. To fit the terminals you will need a non-insulated terminal crimp tool such as . The more basic ones will work, but the ratchet tool is far nicer to use and well worth the extra few quid. Each pack has a male and female block and the requisite latched terminals. When fitting block using block connectors we recommend applying a small amount of ACF50 corrosion block grease or electrical silicone compound to the terminals before finally pushing them together to protect them from moisture, making the wiring far more reliable and longer lasting