US  2,835,634 <br/>
Polyethylene expansion material. 

 -  May. 20, 1958 
<br/><br/> cl.252/4 
<br/><br/><label>Subjects--Local Terms: </label><br/>POLYETHYLENE <br/>EXPANSIBLE MATERIAL <br/>SWITCH <br/>VALVE 
<br/><br/><label>Call Number: </label>US 2,835,634