USER MANUAL LINK – https://www.google.com/url?sa=t&source=web&rct=j&opi=89978449&url=https://www.uzimex.cz/soubory/20061116_dh-7_navod_en.pdf&ved=2ahUKEwiizYuJzI2KAxXaTGwGHT8oGzoQFnoECBsQAw&usg=AOvVaw0fsYejNXC2XKtVWBTNhjY2
Diavite DH-7 Roughness meter