Theo Wanne's new feeler gauge set includes all sizes needed to accurately measure a mouthpiece tip opening and has both US and Metric numbering. There is even a big 3mm (.118") gauge included. You no longer need separate sets of feeler gauges for inch and metric; you only need this one. Use this feeler gauge set with one of Theoi Wanne's glass gauges to measure the facing curve on any saxophone or clarinet mouthpieces.