Ring spanners, curved, metric. Standards: ISO 691, ISO 7738, ISO 3318, ISO 1711-1 and DIN 3113. Material: high alloy quality steel. U-shaped shaft for better comfort. Position of the jaw 15 with flatter heads for better accessibility. Twelve-sided Dynamic Drive profile for a longer service life of screws and nuts. Ring side 15 curved for hand protection and better grip. Larger and bilateral exact measurements for improved recognition. Chrome-plated, finely polished for high surface quality. Patented U-shape design. SB = individually packed on an informative plastic card.