Pentel of America, Ltd. Products - Lead Refill, 3H Hardness, .5mm, 12/TB, Black - Sold as 1 TB - Super Hi-Polymer Leads are designed for automatic pencils. Made with a patented manufacturing process that provides greater lead strength, a darker line and minimal breakage. Pentel of America, Ltd. Products - Lead Refill, 3H Hardness, .5mm, 12/TB, Black - Sold as 1 TB - Super Hi-Polymer Leads are designed for automatic pencils. Made with a patented manufacturing process that provides greater lead strength, a darker line and minimal breakage.