When you enter an item which requires dimensions a pop-up window will appear in which you can add them.  Make sure you use inches and pounds for measurements/dimensions (e.g.1, 2, 1.5, or 0.25 (leading zero for partial lbs or inches).

ScanPower automatically sends a dimension-only feed and sets the item aside while we wait for Amazon to process it.  This usually takes 5-15 minutes.

Once the dimensions have been accepted by Amazon the item will appear READY below the shipment grid.