CTA Tools A311 25-Blade Extra Long Feeler Gauge is designed for long reach applications, especially diesel. There are 25 removable blades, each 12-inch long, that have metric markings. Blade sizes are 0.0015, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.010, 0.011, 0.012, 0.013, 0.014, 0.015, 0.016, 0.017, 0.018, 0.019, 0.020, 0.021, 0.025, 0.027, 0.030 and 0.040-inches. Whether tuning up your ‘68 Corvette or changing the oil on a John Deere tractor, CTA can supply you with the tools needed to do the job.