This single fuse holder has so much potential. Alone it can be used with either ANL or MANL fuses. It supports 4ga wire or remove the adapter and insert 1/0 ga wire. The magic happens when you combine two or more of these to create a fuse block that can be configured to virtually any use. You can parallel two of them and attach a bus bar on one side then connect 1/0 input and have two 4ga output. Connect multiple units and connect bus bars at all inputs to create a ground distribution. These will be my go-to fuse holders from now on.