HOUSTON -- The Astros added four players to their 40-man roster Friday in advance of the deadline to add players to protect them from being exposed in next month's Rule 5 Draft.

By purchasing the contracts of right-handed pitchers David Carpenter, Jorge DeLeon and Arcenio Leon and infielder Jimmy Paredes, the Astros' 40-man roster is now full. Carpenter and Paredes were both acquired in midseason trades earlier this year.

Carpenter, 25, went 6-4 with 20 saves and a 2.51 ERA in 55 relief appearances combined with Class A Palm Beach and Class A Lancaster this season. He was acquired by the Astros from St. Louis on Aug. 19 in exchange for infielder Pedro Feliz.

Carpenter is a converted pitcher, having spent his first two years of professional ball (2006-07) as a catcher. In 2008, he converted to the mound and has gone on to post an 11-7 record with 35 saves and a 3.27 ERA in 122 career appearances.

De Leon, 23, posted a 2-1 record with six saves and a 0.64 ERA in 23 relief appearances for Tri-City this season, the Astros' short-season Class A affiliate. Like Carpenter, De Leon is a converted pitcher, having spent the last four seasons as an infielder in the Astros system. He was originally signed by Houston as a non-drafted free agent out of the Dominican Republic in 2006.

Leon, 24, went 2-4 with four saves and compiled a 3.97 ERA in 44 relief appearances combined with Class A Lexington and Double-A Corpus Christi in 2010. He began his season at Lexington, posting a 2.33 ERA in 26 games before his July promotion to Double-A. The 2011 season will be his seventh in the Astros system, after signing as a non-drafted free agent out of Venezuela in 2005.

Paredes, 21, hit .287 with 34 doubles, seven triples, eight home runs, 65 RBIs and 50 stolen bases in 133 games combined between Class A Charleston and Class A Lexington last season. He finished second in the South Atlantic League in hits and third in stolen bases.

Paredes was acquired midseason from the Yankees as part of the Lance Berkman trade. After his acquisition, he played primarily second base but also saw time at shortstop and third base in 2010. A native of the Dominican Republic, Paredes was originally signed by the Yankees as a non-drafted free agent in 2006.