I use a digital Ohaus CS5000 http://www.ohaus.com/products/view/overview.asp?HKEY=001001003003&Source= which has a 5Kg limit. It is accurate to 0.1oz. There is a 2Kg Cal weight available that I have but you don't really need the Cal weight. In the 4 years i have had the scale it is has never changed. I purchased this scale from ITIN.
Most of the above mentioned methods are suspect and if you want to give an accurate weight of your doubles, you need precision equipment.-Dick