FYI, Dessalator originally made the membrane tube end caps out of white nylon. Emek copied Dessalator. Dessalator's choice of Nylon proved to be the wrong choice. Dessalator later made end caps from a harder material which was black. I am not sure of what the black material is, but, in my experience is that there have been very few issues with the Dessalator black end caps.
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