The Bucks announced Monday that they had signed Mason to a three-year contract extension, meaning that the fourth-year player is signed through the 2006-'07 season. Financial terms were not released although, according to a league source, the extension is worth $21.699 million. Mason, whose salary is about $1.9 million this season, will make $6.429 million, $7.233 million and $8.037 million in the next three seasons.