Millimeters (units of length) to ounces (units of weight) with unknown volume is not a very reliable conversion system.
The volume of the profile will be different depending on the shape of the profile all the time, and sometimes significantly.
Also, different manufactures use different tungsten alloys that will differ in density, therefore in weight.
Here is correlation of size in millimeters, weight in grams and ounces, and hook sizes for another product:
http://www.raremonster.com/product/tungsten-jigs/
My favorite site is 5mm (~2 grams ~1/14 oz). Small enough for finicky fish and heavy to be sensitive even in great depth and extreme cold.
What I see, people use mostly 5 and 4 mm and 3mm when the bite is slow.