I believe it is for a triple. I have one on my 73 Paramount P 15, and if my recollection is correct that is how the spindle was marked.
They certainly did exist back then!
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1971 Paramount P-13 Chrome
1973 Paramount P-15 Opaque Blue
1974 Raleigh Professional Blue Mink
1991 Waterford Paramount
Holland Titanium Dura Ace Group
Holland Titanium Ultegra Triple Group