The thing I've noticed with my past experiences mailing by Tracked vs Small Packet Air to the USA (from Calgary), Tracked normally arrives in under 10 business days. Small Packet Air can take up to 15 business days, (slightly longer than what eBay currently states). If a customer hasn't received their item and is getting irritable I just ask them to be patient and normally it shows up a day or 2 later. These times are for continental USA. Alaska/Hawaii/PR/APO's/FPO's will be slightly longer.
And customs can affect delivery times if there are issues in clearing.
-CM
