The Giants announced the moves Monday, two days before the start of free agency.
Entering his eighth season, Herzlich was an unrestricted free agent. He spent last season on injured reserve after sustaining a stinger in training camp. The 30-year-old made the Giants as a free agent in 2011. He has played in 88 regular-season games with 17 starts.
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Halapio played in his first career regular-season games last season. He spent the first four weeks on the practice squad and was signed to the active roster on Oct. 4. He started the final six games at right guard.
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