Southend United have completed the signing of Charlton Athletic defender Harry Lennon for a nominal fee.
The 23-year-old played 12 times for the Addicks last season.
Lennon came through Charlton's academy and has spent time out on loan at Gillingham and Cambridge United in the past.
"I'm really pleased to bring Lennon to the Club, I've kept my eye on him for a number of years and he has the attributes and attitude to be a top player," manager Chris Powell said.
"He will give us good competition in the centre back area, he has pace, he is left-footed and can handle the ball well which will give us balance in defence."
Southend have also sealed a permanent move for midfielder Sam Mantom who had a successful loan spell at Roots Hall last season.
The 26-year-old has joined on a two-year deal after the Shrimpers agreed an undisclosed free with Scunthorpe United.
Elsewhere in League One, Peterborough United have sold left-back Andrew Hughes to Championship side Preston North End and striker Ricky Miller to Port Vale.
Meanwhile, in League Two MK Dons have signed Macclesfield Town's Mitch Hancox on a free transfer and midfielder Joel Byrom has re-joined Stevenage following his release by Mansfield Town.