There are many varieties of “Milky” oolongs; some being infused with the essence of milk, and others which are supposedly “naturally occurring” or aquire their creamy flavor from the nature of the oolong varietal. This is an example of the former; being scented with milk in much the same way that jasmine tea is scented with real jasmine flowers.
Personally, I prefer the scented milky oolongs, as the “naturally occurring” ones only vaguely hint at a milky flavor. There used to be a purveyor in my area who carried this outstanding tea, and I tracked it down to Red Blossom. Mr. Luong at Red Blossom carries an Anxi and a Taiwan version of this tea, the former being darker roasted. It was this Anxi Silk Oolong which I had first encountered at my local teashop, and I was very happy to find it again!