"This deal gives us two talented young pitchers as we continue to create competition in camp," Rangers general manager Jon Daniels said. "Jenkins is a local player we've scouted for some time. Feigl we liked quite a bit in spring 2015 -- he's now healthy again and ready to go."
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Jenkins has been assigned to the Major League roster, keeping the Rangers' roster at 40 players. Feigl has been assigned to Double-A Frisco.
Jackson, 25, has made 15 Major League relief appearances over the last two seasons. The Rangers shifted him to the bullpen in 2015, and he posted a 4.86 ERA with 59 strikeouts in 46 1/3 innings between Frisco and Triple-A Round Rock in '16.
Jenkins, 24, was 2-4 with a 5.88 ERA in 14 games (eight starts) at the Major League level this season.
Feigl, who turns 26 later this month, appeared in six Rookie-level games this season, throwing six scoreless innings.
Cash Kruth is a reporter for MLB.com. Follow him on Twitter at @cashkruth. This story was not subject to the approval of Major League Baseball or its clubs.