t oz:

A troy ounce (t oz) or (toz) is a unit of measure used for weighing precious metals that dates back to the Middle Ages.
Originally used in Troyes, France, one troy ounce is equal to 31.21 grams, according to the U.K. Royal Mint.


kg:

The SI unit of mass, equivalent to the international standard kept at Sèvres near Paris (approximately 2.205 lb).
The kilogram or kilogramme is the base unit of mass in the International System of Units. Until 20 May 2019, it remains defined by a platinum alloy cylinder, the International Prototype Kilogram, manufactured in 1889, and carefully stored in Saint-Cloud, a suburb of Paris.


By the way, this app is useful for converting amounts from kilogram to troy Ounce and vise verse.