The PTB Cal15 is a certified wieght set that comprises of a 5, 10 and 15 kg weight that is used to calibrate all Pharma Test and other manufacturer's hardness tester load cell. According to the latest USP , the PTB Cal 15 can be used to fulfill the 3-point calibration requried. Furthermore, the PTB Cal15 offer a notched center to easily balance on the load cell. The unit comes complete with an NIST traceable certification and allows the user to perform do-it-yourself calibrations.