WHEELS MFG Seat post gauge

•  Covers 24 common seatpost sizes, from 25mm to 34.9mm, including all the intermediate sizes you're likely to encounter.
• Simply insert the gauge into the seat tube until it fits perfectly, no batteries, no guesswork.

Features:

• Precision-cut acrylic gauge for long-lasting use
• Measures inside diameters of seat tubes from 25 mm to 34.9 mm.
• Includes common sizes: 25.0, 25.4, 25.6, 25.8, 26.0, 26.2, 26.4, 26.8, 27.0, 27.2, 27.4, 28.2, 28.6, 28.8, 29.2, 29.4, 30.0, 30.2, 30.4, 30.8, 30.9, 31.4, 31.6, 31.8, 34.9