These measure approx. 3/4" X 3/4", and are not marked, except as to PAT. NO. 2974381, which was done in the 1950's. Please look at all photographs, as they are part of the description and ask any and all questions prior to looking. Thanks! Launched from my store - Powered by Highwire.com Track Page Views With Auctiva's FREE CounterEvery buyer gets a MyStoreRewards invitation for cash back