Black 3/4" ID PVC tubing shrinks to 3/8" ID when heat is applied. Insulates and protects individual connections or entire wiring harnesses. Provides a strain relief that protects against vibration damage. Meets MIL-I-23053/2 Class 2 specifications. A heavy-duty hot air gun is recommended for shrinking, but a high-wattage hair dryer can also be used. This size fits our 4 gauge battery cable and terminals.