Crawley have signed former Millwall defender Ronnie Bull following his exit from Conference rivals Grays Athletic. Bull, who can also play on the left-hand side of midfield, has also had spells with Grimsby and Rushden.
The 26-year-old has been given squad number six by the Red Devils and is expected to make his debut at Aldershot on Saturday.
Meanwhile, Crawley striker Jake Edwards is expected to complete his move to Tamworth this week.