The aluminium foil membrane has a mylar™ {HEAD ~ backing} which enables the foil to withstand {TAIL ~ the pressure difference} across it due to the gaseous environment outside the chamber and the substantial vacuum within 
The aluminium foil membrane has a mylar ™ { HEAD ~ backing } which enables the foil to withstand { TAIL ~ the pressure difference } across it due to the gaseous environment outside the chamber and the substantial vacuum within
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