I am going to guess that this is simply a product offered by Bank of Guam that earns SkyMiles through a partnership with Delta. Beyond that, I doubt there are benefits, such as bonus MQMs, helping to meet the MQD threshold waiver, etc. The Pacific Islands in that area have a unique relationship with Delta. I visited a friend in Palau in 2015 and I was able to earn SkyMiles at a local grocery store by having them enter my membership number in the cash register at checkout. I knew that was offered simply by a sign hanging in the window that said something like EARN SKYMILES HERE. Never seen anything like that before or since anywhere else in the world. Lastly, the Bank of Guam will service such a relatively small population as compared to AMEX that I equate it to any of the other credit card partnerships, such as the ones offered in foreign countries that earn miles per dollar (or whatever currency) spent but no other benefits.