silver rings

Heea List,
I won an unknown Triumph item in Richmond at the Triumph Convention auction
for a grab bag of items.  Could someone please tell me what it is and if I can
adapt it for my TR3A?  The item is actually four silver rings, made of
aluminum, with a inside diameter of 2 7/8" and the outside diameter is 3 3/4",
and their about 1/2" thick with a 1/4" lip.  What are they?
Thanks, Paul Dorsey