... coring crowns,electric coal drill bits, coal cutting picks,oil cone bits andscraping knife bits,used in geological prospecting,coal ... 486.52700Largely for the inserts and buttons of percussion bits and tricone bits to cutmedium-hard, hard and very hard formations. ... YG13C14.2862850Primarily for the buttons of tricone bits and inserts or rotary percussion bits tocut hard and very hard formations. ...