If you have lost some weights, or need additional weights for extra heavy tracking, US coins can be used with excellent accuracy:

US Penny (1Cent):  2.5 Grams

US Dime (10 Cents):  2.3 Grams

US Nickel (5 Cents): 5.0 Grams

US Quater (25 Cents): 5.7 Grams