Rudi: The set I have measure as follows: The main plate is 12 .250" X 4" X .375". The hole spacing is .625" in from the corners then spaced 2.750" apart down the sides and .625" from the edge for a total of 10 holes. The hole diameter measures .555". I hope this all makes sense. The set also came with a set of spacers that measure: .850" O.D. X .585 I.D. X 1.125" long.