I agree that it depends on the smoker, diameter and length etc. Even at that they vary. I have a 16" Horizon convection plate in mine. Prior to buying it I borrowed one from a friend at work, from the same manufacturer. The holes in mine were all about 1 size larger than his. I don't know the sizes since I haven't actually measured them. I did think his worked a little better with the smaller holes. I could measure mine if that would help? smittyjonz is pretty close on the sizes I think