I carry a pool bag (canvas) and inside are all my toys to fix. shape and repair my cues. Inside are six cue balls: 2 Measles Cue Balls (1 new & unused), 1 Red Dot Aramith Cue Ball. 1 Aramith Red Logo Cue Ball, 1 Centennial Cue Ball & 1 Jim Rempe Training Cue Ball.
Pool ball sets in pool halls have varying weights. I also carry a calipers in my case and a electroinic gram scale. I have that to measure & weigh pool cue & shafts. I can easily determine which cue ball is best matched in weight to any pool hall set of balls.
The bottom-line is I only play with pool balls at the local pool halls in weekly tournaments. All the other times I use one of the two sets of Centennial pool balls I own that I rotate for play. I use the Measles Cue ball with my Centennial sets and it's the identical weight (almost)......169 grams vs. the Centennial set (168 grams).