I live in a metric country, but when I go to the market we're still using 'pond' (pound) and 'ons' (ounce). They mean approximately 500 grams and 100 grams resp

I live in a metric country, but when I go to the market we're still using 'pond' (pound) and 'ons' (ounce). They mean approximately 500 grams and 100 grams respectively.