very tool in the Salisbury Insulated Socket Set is rated for exposure up to 1000VAC and dielectrically tested at 10,000VAC. These tools meet or exceed ASTM F1505-01 and IEC 900 Standards for Insulated Hand Tools. They are necessary for compliance with OSHA 1910.333 (c)(2), and NFPA 70E 2004.
The insulating material used is impact resistant and flame retardant. Two-color insulation makes inspection easier which adds to the overall safety. If the yellow under layer is showing, the tool may no longer be insulated properly and should be considered for replacement and shall be removed from service.