For the best performing electrical splice, use these 12-10 Gauge Yellow Heat shrink butt connectors. American made high quality heat shrink insulated butt splice with 20% more copper than competing imported splices. Provides the ultimate in protection to keep moisture, chemicals, and contaminants from ruining your 12 gauge and 10 gauge wires. Secure the butt connector to your wire using the yellow crimp nest on any standard pair of wire crimping tool. Then apply heat from either a heat gun or torch to shrink the insulation and release the adhesive. Once done, the connection will be sealed and secure. Excellent for use in automotive, marine, and RV applications, but the 600 volt maximum voltage rating means that these heat shrink butt connectors can be used in most electrical applications.