Tekton L-keys are made with 8660 nickel chromium molybdenum steel that's heat-treated to HRC 54-58 to produce tools that are hard, but not brittle. As a result, the maximum torque of the L-keys consistently exceeds the ASME standards for minimum torsion load and the ISO standards for minimum proof torque. The star-shaped ends have 6-lobes that are machined to precise tolerances for an exact, high-torque fit with Torx fasteners that resists camming out. The L-keys are coated with a durable manganese phosphate finish that's resistant to corrosion. With the exception of the smallest sizes, L-key sizes are marked in two ways-both with a high-visibility laser marking and a stamped marking.