Mitutoyo Surface Roughness Small Hole Detector - 2X Length The Standard Detector for the Mitutoyo Surface Roughness Tester model SJ-400 series has a measuring tip that is about 7.6mm overall height and has an Overall Length of 44.7mm. To be able to measure the surface roughness of a small hole, Mitutoyo recommends using the Small Hole Detector for the Mitutoyo Surftest SJ-400 series. The Mitutoyo Surface Roughness Tester models SJ-411 & SJ-412 are both available in 2 different models, the Standard Force model and the Low Force model. The Standard Force model uses 4mN measuring force during the measurement. The Low Force model uses 0.75mN measuring force during the measurement. This Small Hole Detector is designed to be used with Both models of the SJ-411 & SJ-412. Features include... Small Hole Detector for Mitutoyo Surftest Models... SJ-411 SJ-412 Stylus Profile: 5µmR Tip Radius Overall Length: 94.4mm 90° Tip Angle