You don't even need to set up an account with them. I also think they make it easier to track a package and have good notifications.
I also found estimating the cost is much easier than FedEx and UPS because you can play around with the dimensions and weight to see what the best price would be.
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84 Bridgestone 400. 90's Basso Highway, 07 Rivendell AHH, 16 Clockwork All-Rounder , 22 Rivendell Roadini