Reed's 0SP3/8 is a Block Die. It has a 3/8" capacity. It weighs .6 lbs. This block die features a wide throat and extra fine threads that acutally pull the die onto the pipe, even if the burr is large. It's CNC-milled from solid tool steel, and give you a lower cost and lighter weight than other block dies. This die is designed to be used with Reed Threadguard Cutting Oil for better and faster threads and longer die life. This die measures 2" X 2", and can be used with the following stocks: S81, SD81, 81, and 71D.