Tower crane foundation types

Ball mason jar identification

Feb 04, 2012 · 2. Reaction score. 0. Points. 0. I have a 2quart blue Ball Perfect Mason jar with KKK on it. It has 3 K's,in a row, in between the threads on top (where you screw the cap on). It has a number 10 on the bottom.Does any one know about this jar and why the K's are there?