48 ounces of a ~5% beer is 4 standard US drinks. In most people, with an EtG test that would be detectable out to 24-36 hours, but not 48 hours. read more
This is mostly marketing propaganda by testing labs: Real-world testing shows that 1-2 drinks aren't detectable after 24 hours, and in most people 3 are sometimes detectable in that period, while 4-5 are consistently detectable -- but none of those are detectable at 48 hours. read more