The Fowler-Bowers Holemike Bore Gage Set offer an economical solution to accurate shop floor bore measurement. Fast, accurate and easy-to-use, the wide application range of the Bore Gage line may be purchased individually or in sets. Included in this set are the following... 4.0" - 8.0" / 100-200mm Measuring Range 0.00005" / 0.001mm Resolution 4 Measuring Heads 1 Handle 2 Setting Rings Features include... 3-point contact point heads IP67 Rated Protection Ratchet Stop for consistent measurement Bluetooth Output