Dura Lead replacement lead is designed exclusively for the STKR mechanical carpenter's pencil. This package includes 4 pieces of Black Dura Lead packed in a durable storage tube. Dura Lead is 18% thicker than traditional carpenter pencil lead, Medium density and stands up to the rigors of construction. Dura Lead's patented grooves lock into place and never slip while being held by the Mechanical Carpenter Pencil's rugged jaws. Quickly shape the lead for a razor sharp tip that is still durable. Get closer to a speed square than any other pencil. Never sharpen a carpenter's pencil again.