The accurate sharpening of the needles minimizes the pain associated with the treatment. Ultra-thin diameters (0.3 and 0.23 mm) make the product excellent for sclerotherapy treatments. 712315: inner diameter 0.18 mm versus 0.16 mm standard needle 27G/12 mm code 712305. 712318: inner diameter 0.28 mm versus 0.22 mm standard needle 30G/13 mm code 710306.