Steven Kampfer, a depth defenseman who played 35 regular-season games and three more in the playoffs, had his contract extended for two years. He would have become an unrestricted free agent on July 1.

They’ve still got bigger deals to attack on their free agent list, but the Bruins made a move on Tuesday to keep some of their defensive depth off the open market.

Steven Kampfer, a perceived throw-in last September when the B’s sent Adam McQuaid to the Rangers, signed a two-year extension at $800,00 per season. Kampfer, 30, previously a Bruin in 2010-11 and ’11-12, was scheduled to become an unrestricted free agent on Monday, July 1.

Kampfer, who played for the Wild, Panthers and Rangers before returning to the B’s, was eighth on their defensive depth chart when he arrived in last season’s training camp, but went on to play in 35 regular-season games and make the first three playoff appearances of his NHL career -- one game each against the Maple Leafs, Hurricanes and Blues. He was especially valuable during the first half of the season, when all seven defensemen ahead of him were sidelined at some point by injuries. Once the defense corps healed, he went through a stretch when he didn’t play a game from Dec. 23 and March 12.

The Bruins still have defensemen Charlie McAvoy and Brandon Carlo to re-sign. Both become restricted free agents on July 1. Kampfer and John Moore are currently the only defensemen with contracts through the end of next season.

DEVELOPMENT CAMP OPENS: The Bruins’ annual Development Camp opens Wednesday and runs through Friday at Warrior Ice Arena, with 34 prospects scheduled to attend. Nineteen are players the Bruins have drafted or under contract, including first-round selection John Beecher and three others picked during last weekend’s NHL Entry Draft in Vancouver.

Among the 15 players attending on an invitation basis is Mike Hardman, a forward from Hanover who is scheduled to play next season at Boston College. Hardman, 20, played for two seasons at Xaverian Brothers High School before spending 2017-18 at Des Moines (United States Hockey League) and last season with West Kelowna of the British Columbia Hockey League, where he scored 39 goals and 72 points in 59 games.

SCHEDULE ANNOUNCED: The Bruins’ 2019-20 schedule was announced on Wednesday, with the B’s among the last teams in the NHL to play their home opener: They visit the Stars (Oct. 3) and Coyotes (Oct. 5) for those teams’ home openers, then visit the Golden Knights and Avalanche before hosting the Devils at TD Garden on Oct. 12. Only the Kings and Wild play their first home games so late.

The B’s will then play eight of 10 games at home after the season-opening trip. That stretch that includes an Oct. 26 visit from the Blues, who won Game 7 of the Stanley Cup Final at the Garden on June 12.