These Holtests are versatile, self-centering three-point internal micrometers for the accurate and efficient direct-measurement of internal diameters. Three anvils, evenly spaced at 120° apart, contact the internal wall surfaces and find true alignment with the axis of the bore for accurate ID measurement. TiN-coated measuring contact points(over 6mm/.275" range models) provide excellent durability and impact resistance and allow the instrument to measure right to the bottom of a blind hole. Highly durable because of carbide-tipped contact points (anvils). Measurement can be taken closer to the bottom of the blind bore. Can measure deep holes using an Extension rod (optional) which is available on models over 6mm (.275") measuring range. With Ratchet Stop for constant force. Setting Rings for zero point adjustment are optional. Supplied in wooden case.
368-915 Holtest set of four complete gauges (micrometer head units and measuring heads for each size) and extension rod in wooden case.