Drill-Its Phoenix set of drill bits are our range of Standard PCD coring tools, meaning that they use Core Barrel Drill-Line Inner Tube Plastic Liner consisting of a clear, thin-wall extruded rigid plastic tube of which by accurate manufacturing processes is manufactured to close tolerances on both the outside and the inside diameters. Clearance between the O.D. of the “Drill-Line'' and I.D. of the Core Barrel inner tube is therefore carefully controlled and allows easy fitting of the Plastic Tube into the inner tube in the field. When the clear plastic material is used (inserted) it will not contaminate the Core sample during drilling and encapsulation. The material does not absorb water and will not swell or change shape