Polyimide tubing with IDs down to 0.004-in. and wall thicknesses as thin as 0.0005-in. are available from MicroLumen Inc. High Performance Medical Tubing, Tampa, Fla., (microlumen.com). The company contract manufactures sizes to 0.086-in. ID and custom diameters are available. The tubes are made by coalescing the thermoset plastic around a core that is later removed. Tolerances can be controlled to ±0.0002-in. on the ID. The tubes are used in catheter shafts, predominantly in cardiovascular and urological devices. Small diameters minimize patient trauma. PTFE and various composites are also used for specific lubricity and bonding problems. The tubes are rated USP Class VI for biocompatibility. Polyimide tubing is available in various colors and material combinations. For stiffer or kink-resistant tubing, braiding and coiling designs encapsulate stainless-steel wire (down to 0.001-in. dia.) into the tube. Laser machining, sub-assembly, flexible tips, custom holes and shapes, and marker bands are also available.