Manually-operated tensioner tools for polypropylene strapping tighten strapping before the ends are secured using a seal and sealing tool. Correct tensioning ensures bundles or packages are secure during shipping or storage, and help prevent over tensioning that can damage boxes and contents. They can be carried to the work location and do not require an external power source or attachments, so are often used in low-volume applications or where access to a power source is limited.