Anyone use these markers?

[slicer79]

http://m.rockbottomgolf.com/nike-golf-challenge-coin-ball-markers.html

Anyone used these markers?

Just wondering how big they are? I know it says 39mm but I'm wondering are they big & chunky like the poker chip markers.

 

[ScienceBoy]

How many extra yards off the tee does it promise?