Japanese Style Crimson IronsMade using DC53 steel. Comes sharpened with an antique finish for a firmer grip. Slim diamond shaped teeth creates smaller, refined holes. 3mm ~8. 5 spi, 3. 25mm 8 spi, 3. 85mm 7 spi, 4mm ~6 spi, 5mm 5 spi The 5mm irons are approximately 1mm larger to cater for thicker threads. 2. 7mm irons comes in 2, 6 and 10 teeth. All other sizes come in 2, 5 and 9 teeth. Irons go fast, therefore we have a steady flow of these sets in and out in case your selected