the closure device 10 according to the present invention the closure device 10 includes a plurality of pressure ports 34 and a first closure composition port 20 and a second precursor entrance port 46 an energy delivery port 30 is coupled to a plurality of energy delivery devices 28 the closure device 10 includes a guidewire lumen 48 for use with the method described in fig6 a 6g when the position sensing mechanism 34 is a contact switch or a pressure port the position sensing mechanism 34 is preferably positioned at least 25 mm from the distal end 16 this positioning assures that the distal end 16 of the closure device 10 remains within the vessel 60 when the closure device is positioned to deliver the closure composition precursor this feature reduces the risk of delivering the closure composition precursor to an improper location on the vessel or within the vessel fig1 a and 10b illustrate another position sensing mechanism 34 a balloon 98 is coupled to the distal end 16 of the closure device 10 by a first and second retaining collar 99 the balloon is positioned over an inflation port 100 the balloon is coupled to an inflation bulb 102 by an inflation lumen 104 and an inflation tube 106 the balloon 98 is deflated when the closure device 10 is positioned within the vessel 60 once the balloon 98 enters the vessel 60.