a stent deployment device is provided with a tapered balloon wrap to protect the edge of a crimped stent during stent deployment . the balloon is wrapped unevenly so that the distal end is looser and has a wider circumference than the proximal end of the balloon . with a stent crimped upon such a balloon , the distal balloon end billows out and covers the distal edge of the stent . this shielding billow prevents the stent edge from becoming damaged or causing harm if the stent is distally impacted while traversing body vessels on the way to the deployment site .