The Lange skinfold caliper calibration block is made of aluminum and will test calibration at 10mm, 20mm, 30mm, 40mm, and 50mm. While it is designed for the Lange caliper it may have other applications as well. Note that it will only test the calibration; it will not calibrate your equipment, and a skinfold caliper is not included. Because skinfold calipers use metal springs, over time the calibration accuracy can change. Check the reading of the caliper with this block at each increment. If it is off by more than 1.0 mm, consider getting it calibrated by a professional. Or, continue to use it and adjust your results.