Black Friday: lifetime access is on a special offer in the app, until November 30. Black Friday: special offer on lifetime access, until November 30. Download
이 경도계는 금속의 경도를 측정하는 데 사용됩니다.I gyeongdogyeun geumsogeul gyeongdoreul cheugjeonghaneun de sayongdoemnida.This hardness tester is used to measure the hardness of metals.