This precise set of 20 feeler gauges is perfect for measuring string action, nut slot depths, fret slot width, string to fret clearance, and other critical measurements.  Made of steel, and marked in metric and inches, this set of feeler gauges is perfect for setting up both US-made and import instruments.  Allparts #LT-1703-000.  

20 gauges:

• 04mm (.0015")
• 05mm (.002")
• 06mm (.0025")
• 10mm (.004")
• 15mm (.006")
• 18mm (.007")
• 20mm (.008")
• 25mm (.010")
• 30mm (.012")
• 35mm (.014")
• 40mm (.016")
• 45mm (.018")
• 50mm (.020")
• 55mm (.022")
• 60mm (.024")
• 63mm (.025")
• 65mm (.026")
• 70mm (.028")
• 75mm (.030")
• 80mm (.032")