Features0.5mm HB Refill leadSuitable for all 0.5mm mechanical pencilsAbout 10% stronger than any other Pentel refill lead thanks to a ceramic cell structureSmoother than other refill leads on the market40 leads per tubePentel Ain Stein C275 0.5mm lead. The new improved Pentel Ain formula utilises a molecular ceramic frame to support the graphite and lubrication particles. This greatly improves strength, enhancing break-resistance of the Pentel Mechanical Ain Stein Pencil Refill Leads 0.5 HB while continuing to provide superior smoothness and darkness. Pack of 40 0.5mm x 60mm leads suitable for all 0.5mm mechanical pencils.