Sensidyne 2, 2-Dichloroethyl Ether Gas Detector Tube 223S, 2-30 ppm, 2x5 Tubes/Box. (Special Order Item) Buy 1 box gas tubes at regular price, get $10.00 off additional box purchased. Valid on orders shipped to 1 location in Continental United States. If buy more than 12 boxes, please call.