Toe Nail Cutter Barrel Spring with Back Lock Available Sizes. 4.5 in, 5.5 in Details. Implements produced for professional usage are made of Japanese stainless steel J/2 - 420, HRC° (hardness) 52° - 55°. Implements produced for personal usage are made of superior quality stainless steel 410, HRC° (hardness) 45° - 48°