. . "However, the fittings and delivery systems of the invention are equally effective at positioning and securing all types of bypass grafts, biological and synthetic. [0061] Synthetic bypass grafts may be manufactured by extruding, injection molding, weaving, braiding, or dipping polymers such as PTFE, expanded PTFE, urethane, polyamide, polyimide, nylon, silicone, polyethylene, collagen, polyester," . .