Black PVC tubing shrinks to half its original diameter when heat is applied. Insulate and protect individual connections or entire harnesses. Provides a strain relief that protects against vibration damage. Meets MIL-I-23053/2 Class 2 specifications. A hot air gun is recommended for shrinking, but a high-wattage hair dryer can be used. With this assortment, you will always have the right size on hand and save over 13% off the normal per foot cost. Contains three feet each of part numbers 4020, 4021, 4022, 4023, 4024 and 4025 to cover everything from 1/16" OD to 1/2" OD.