A particular kind of horizontal directional drilling (HDD) tool used to increase borehole diameter is called a barrel reamer. The reamer can cut and open a hole that is slightly larger than the diameter of its solid body thanks to the relatively flat face that is equipped with rows of carbide cutters. The slurry was able to flow through the reamer due to the reamer's teeth overcutting the tool body.

Full diameter compaction, fixed conical carbide cutters, carbide hard surfacing in critical wear zones, replaceable fluid ports, and specialised wear bars with carbide hard surface to protect fluid ports are some of a barrel reamer's key characteristics.