The Bills traded defensive end Eli Harold to the Eagles in exchange for offensive lineman Ryan Bates, the teams announced Friday.
Bates, 22, signed with the Eagles as an undrafted free agent in April. The offensive tackle was getting mostly third-team reps in Philadelphia.
The Bills lost two more offensive linemen to injury in their first preseason game. Conor McDermott is in concussion protocol, and Russell Bodine had an oblique injury.
Ty Nsekhe did not practice with the team on Friday, and Mitch Morse remains in concussion protocol.
Bates made 14 starts at left guard and left tackle as a freshman, eight starts at left tackle as a sophomore and 12 starts in the 2018 season, with nine coming at left tackle and three at right tackle.
The Bills signed Harold this past offseason, but he was buried on the depth chart. Harold was getting third-team reps.
Harold, 25, played for Detroit last season after three years in San Francisco. He has played 61 games, with 25 starts, and has made 94 tackles, nine sacks and a forced fumble.