Model URG -Underreamer Guage

The Holte URG (Underreamer Guard) Underreamer has an extendible arm bit and is considered superior to a one-sided UR because three (3) to four (4) arms extend to ream a full gauge (360 degree) hole. The underreamers which swing out on only one side drill slower and not always straight. This bit design was developed at Holte Manufacturing while researching faster ways to drill large diameter holes. Because there is bit surface reaming the full gauge of  the hole, this bit wears much better than an eccentric style bit which only reams with about a 50 degree portion of  the hole.