Let's clear this up
GDtrailer pointed to a non-insulated crimp tool. That tool is for non-insulated crimp connectors only, such as
These. I prefer this type. A quality tool will provide a very reliable crimp. Then goop it with any of the numerous sealants or RTVs available and heat shrink over it to ooz out the sealant for a good seal.
Then there are the
Insulated Butt Splices. These use a different type of crimp tool. Notice how the tool jaw in the picture is different. You must use this type of crimp tool for any type of insulated crimp connector.
