Featherweight is a weight class, especially for boxing. There is no system of weights that includes featherweights as a unit. Do you mean pennyweight? That is a unit of weight.
One US fluid ounce is about 29.574 mL.
One ounce = 28.349523125 grams
20 pennyweights equal one ounce one pennyweight equals 20 grains or 0.05 of an ounce
20 pennyweights equal one troy ounce. Note that the troy ounce is heavier than a normal avoirdupois ounce.
One ounce is equal to about 28.35 g
It is one fourth of ounce.
One fluid ounce equals 29.57mL
One ounce = 28.349523125 grams
1/2 US fluid ounce = 14.8 mL
There are 2 tablespoons in 1 ounce.
One US fluid ounce = about 0.0296 liters.
28.34 grams equal 1 ounce