It's Like Getting 4 Gauges In One, And Color Coded For Your Convenience. This Gauge Is A Small 1 1/4" Round By 1/4" Thick Metal Disc, Then It Fans Out To Reveal 4 Gauges For Measuring Round, Rectangular And Oval Shapes. So Tiny, And Yet So Handy. The Bright Colors Make It East To Locate The Gauge You Are Looking For.* 4 Gauges In One * 1.25" Diameter * Fans Out To Shape Needed * Fits In Any Toolbox * For Diamonds Or Gemstones