JA Oilfield’s Square Drill Collars and Tri-Collars are run in packed hole assemblies to reduce rapid changes in crooked hole formations. While both afford the needed rigidity to accommodate weight on bit requirements to achieve desired rates of penetration, the Tri-Collar design allows for enhanced fluid circulation and less potential for differential sticking. Square Drill Collars are available in hole sizes 6 inches thru 17 inches. Tri-Collars are available in hole sizes 6 inches thru 12 1/2 inches.