Thanks for all the usefull info.
I can add a little to this thread.
The washers are called reducing washers that are sold at any wholesale house like Platt, Graybar, GE supply.... Look in our local phone book for electrical wholesale.
The washer come in standard conduit sizes.
1/2", 3/4", 1", 1 1/4", 1 1/2", 2", 2 1/2", 3",3 1/2", 4", 5" ,6"
However they are not the size of the conduit.
Example 2" to 1" is acually the O.D. of the pipe. Ususally add 1/2" to the standard size.
You can get any combination like 3" to 1" or 2" to 1 1/4".
It would be best to measure exactly what you needed and go to the wholesale house measure the actual O.D. of the reducing washer.
Hope that helps anyone out there looking for the washers.
They are used in the electrical trade to reduce conduit holes when you cut the wrong hole (I have never done that :roll

, or have an existing part the you need to put a smaller conduit in.