This listing is for standard size Tubular Space & Depth Keys Ace, Ace II, Chicago, Fort, GEM, MEI 7 Keys Cut Blank

ACE, ACEII, Chicago, Fort, GEM, MEI

You will be receiving 7 keys cuts 1-7. 

This is the most popular key size out of all the many tubular/round keys available. 

The O.D. (outside diameter) .377"   9.6mm.

The I.D. (inside diameter) .312"    7.9mm.