Up for sale is a 2009 Big Dog Mastiff Custom Pro-Street Softail Chopper Motorcycle with EXTREMELY LOW LOW VERY WELL CARED FOR 1,539 MILES! The Mastiff offers the outstanding looks of a Hard-Tail Pro-StreUp for sale is a 2009 Big Dog Mastiff Custom Pro-Street Softail Chopper Motorcycle with EXTREMELY LOW LOW VERY WELL CARED FOR 1,539 MILES! The Mastiff offers the outstanding looks of a Hard-Tail Pro-Street Chopperet Chopper