The catheter is a coaxial design catheter with a balloon mounted on its distal tip. The lumen labeled with the balloon size is for balloon inflation while the through lumen allows the catheter to track over a guidewire. A radiopaque band[s] defines the center [or shoulders, if two] of the dilatation balloon. Each balloon inflates to the stated diameter and length at a specific pressure. The balloon size is ± 10% at the Nominal Inflation Pressure. The Rated Burst Pressure (RBP) is different for each size. Check the package label for the RBP. It is important that the balloon not be inflated beyond the RBP.