Britax Marathon convertible car seat in excellent condition!

I'm selling my daughter's Britax Marathon Convertible car seat. We bought it new from Target ($279). A similar one can be found here (https://www.target.com/p/britax-174-marathon-clicktight-convertible-car-seat/-/A-50300055?preselect=51591351#lnk=sametab). This car seat is convertible, suitable for babies and kids from 5 pounds to 65 pounds. We have the original box (see picture). We are a non-smoking family and have no pets.