A clamping device is mounted to the pusher tensioner to clamp a portion of strapping to be applied to a load during tensioning of an opposite end of the strapping. In one example, the clamping device includes a clamping plate mounted to define a clamping space between the clamping plate and a portion of the pusher tensioner. A metal seal having a pusher sealer configuration with serrations on inner surfaces of the metal seal can be used with the tool to secure plastic strapping.