1 x ITL Insulated 1/2in Drive Deep Socket 21mm. The ITL Insulated 1/2in Deep Drive Sockets are fully insulated and exceeds international standards. They have a lifetime guarantee on both the tool and insulation. Each socket is manufactured from injection moulded nylon thermoplastic, and are 100% tested to IEC60900, Category C and ASTMF1505. They are designed to withstand extreme impact, abrasion, and are flame retardant. ITL tools are 100% tested using 1000 volts for 3 minutes submerged in water. They are Category C Impact Tested for operation within a greater temperature range -40ºF to ;158ºF, -40ºC to ;70ºC. 21mm