Fotag 100pcs Insulated Heat Shrink Butt Terminal Connectors Electrical Wire Waterproof Marine Automotive Crimp Grade Set Connector 10-22 AWG Kit Standard crimp and then seal heat shrink butt connectors Dual-walled design, polyolefin tubing in outside and hot melt adhesive in inside. Allows visual inspection, prevents corrosion, and provided a waterproof seal These work great for automotive, marine, and many other applications.