• Underream on all sides of the hole simultaneously with a wing bit system.
• More contact surface than other underreamers results in faster penetration.
• 360° concentric underreaming results in straighter holes than eccentric underreaming.
• Low cost replaceable Arms extend the life of the system.
• Available in RC or Conventional in a variety of Shank styles.
• Tapered Arms and 30° reverse rotation retract the arms without risk of unthreading pipe.
• Less moving parts, bigger arms, and simpler operation than other retractable style underreamers.
• Wears slower than eccentric style (eccentric only reams 50% of the hole at a time).

The Holte URG® (Underreamer Gauge) Underreamer has an extendible arm bit (wing 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.

The Full Gauge UR resembles a conventional hole opener. The extendible arms cover 360 degrees of the hole circumference, minus three air slots, similar in size to a conventional bit. We offer URG Overburden Systems between 10″ – 42″ configured with three (3) or four (4) arms for both conventional and reverse circulation drilling.