Thanks fo reaching out! REI uses multiple carriers, including UPS and USPS, but also LaserShip and OnTrac. Which carrier your package is delivered by depends on a lot of factors including where the item is coming from, cost, location, and timelines to name a few. If you're curious about which would be chosen to deliver to you, your best bet would be to contact our sales and customer service team at 1-800-426-4840 or via live chat. You can also visit our Shipping Timeline page for more information about shipping.
Hopefully this helps, thanks!