I remember opening up a few Silent Giants back in the 1970's. The cases were plastic and easily unscrewed. The insides were filled with something like pearlite or tiny spheres of vermiculite. The pump itself looked like a soup can with no label. Larry Tagrin --------------- See http://www.aka.org/AKA/subkillietalk.html to unsubscribe Join the AKA at http://www.aka.org/AKA/Applic.htm