Arsenal have insisted on some protection with Hector Bellerin's release to Barcelona.
Bellerin has completed a free transfer to Barcelona to end his 11-year stay at Arsenal.
The defender had a year to run on his Gunners deal, but an agreement was reached with Barca to allow him to return to his junior club.
Football.London says the Gunners retain a 25 per cent sell on clause should the 27-year-old end up leaving Barcelona in the future.
This potentially gives them some money for a player that it has previously looked as though they could lose for nothing while they have been able to get a significant salary off the wage books.