these Gas Collection Tubes consist of 15in length of 1/16in O.D. x 1/32in I.D. PTFE tubing with a 19 gauge needle inserted into both ends. The needles have a 22° bevel for septum penetration. Needle permits insertion directy into the MW-80 3 or 5ml conical reaction vial while the opposite end is inserted into a gas collection reservoir.