The internal sidewinder lock mechanism operates using a flat surface key with minimal keyway profiling. A single continuous groove is milled within the center of each side of the blade. The pattern of the groove is determined by each depth of cut. When the key is inserted into the lock, the eight  double-throw, solid-wafer tumblers enter into the grooves through V-shaped openings cut into the tip of the blade. Tumblers are controlled by the left side of the cuts in the key.