Worked like a charm. So much easier than tryingto find a wire to splice into, and can be removed without a trace. Found the circuit I wanted (switched, on key) pulled the original fuse, placed it in the add-a-fuse (bottom slot), put a fuse for my new accessory in the top slot, plugged the add-a-fuse into the now vacant slot in the fusebox. Insert the power lead from my new device into the provided crimp connector, crimp and Done! Just be sure to check the polarity (which side is hot) and plug the side of the add-a-fuse that is AWAY from the accessory lead into the hot side of the fusebox. Otherwise you will be adding the load from the new accesory to the original fuse. The easy test is to install the add-a-fuse with only a fuse for the new accessory in the top slot. Test for voltage on the pigtail. If there is power on the pigtail you're good, if not rotate the add-a-fuse 180 degrees and test again. Don't forget to install the fuse for the original device you're "piggybacking" onto in the bottom slot of the add-a-fuse, and the total load (original plus new accessory) should not exceed 30 amps or you might melt the connector in the fusebox.