In a statement at the end of the 2013/14 Premier League season, Southampton announced on their official club website that they would be leaving adidas, who took over from Umbro at the start of the campaign.
"Following months of discussions at the end of last year, the decision was made at the start of December 2013 that the Club would terminate its contract with its Official Technical Supplier, adidas.
"In February and March of this year, the Club worked hard to repair the relationship with adidas but, despite these healthy discussions, it has become clear that, due to the short lead times involved, adidas were unable to produce a Southampton kit in time for next season."
The adidas kits received criticism and the club's fans were particularly unhappy that adidas had stripped the club's traditional vertical stripes in favor of a red kit with white inserts.
As a result, Southampton have decided to bring operations in-house for at least one season with rumors that Umbro may be back in the near future. The Saints will produce their own range of first team kits and training gear for the upcoming season.
Southampton aren't the first club to do this. Fellow Premier League side Crystal Palace made a similar decision a few seasons back, taking their business to Avec who produced the Eagles' range of kits and training gear without any form of manufacturer branding (except for Julian Speroni's goalkeeper kit).
The Saints will unveil their 2014/15 kits later this month and they will be on sale closer to the end of July.