Scepter's web site for military products
https://www.scepter.com/products/military-products/
And, the listing for the version with smaller tube
https://www.scepter.com/products/mil...4-19-mm-04856/
Perhaps with part numbers it will be easier to find them, I know the last time I was looking none of the system were cheap (at least to my eyes).
A spout on ebay (located in Montreal)
https://www.ebay.com/itm/30382184364...UAAOSw8YRgfvLz