I bought a 4-pack of each of the 3 sizes. They have a tiny amount of play and this is most noticeable with their 25.4 mm Pegs. I'd say less than 1/64" of play with their 5 mm and 10 mm Pegs. I haven't measured. But if you want precision I would definitely avoid their 25.4 mm pegs. As long as there is the least amount of positive pressure from your workpiece against these 5 mm and 10 mm Pegs, then they are what I would consider precise. They appear to mix-and-match well, at least when using the 5 mm and 10 mm Pegs. But, again, I would avoid their 25.4 mm Pegs because of their definite tendency to "lean" with pressure from your workpiece and this "lean" by the 25.4 mm Pegs will not "play well" when using these with the 5 mm and 10 mm Pegs.