1 x ITL Insulated Light T Handle Hex Key 4mm. The ITL Insulated Light T Handle Hex Keys are for use on connector boxes. Made from injection moulded nylon 11, which exceeds the requirements of IEC 60900, the industry standard for live line working. In addition, this tool meets the requirements of Category 'C', which requires it to perform at extreme temperatures of -40°C to ;70°C, making it unique in this category. These insulated tools are the toughest in the market, being virtually indestructible. With a lifetime warranty on both the tool and insulation. 4mm