Bolton Medical produces the thoracic stent-grafts in two types of proximal configuration: RELAY® (uncovered stent-graft) RELAY NBS® (covered stent-graft) Our thoracic stent-grafts will provide you with a very flexible and precise solution for your patient. More than 7,000 patients have been treated worldwide with RELAY® and RELAY NBS® Thoracic Stent-Grafts.