Cambodia local import regulations parcels declared value does not exceed USD300 (and can not be USD300). If your shipments exceed this limit, there will likely be rejected and asked the Hong Kong FEDEX arrange return shipment handling; such as the shipment arrived the local customs will be forced to return the shipment, return shipping by the sender bear 
Those who export to the federal piece of Cambodia, reporting not exceed 299USD, if more than not export, local customs cargo declarations found over 299USD, will be forced to refund the full cost borne by the sender, please know, thank you