We have made our very own chain tightener free for previous problems!
Made for 8-19 mm. Tightening and releasing is quick and easy.
Open and flexible. Hardened jaws and teeths.The top jaw has an extra hook. The chain from the other jaw may be connected to this hook in order to release the bottom jaw and have a new grip further down.
It has a pulling force of 300 kgs!

The backside of the square shaft has teeths and the tightener works as a jack.
This prevents it from slipping during tightening and jamming when loosened up.(See backside photo)

The tightening handle is removable and the other end can be used to open or tighten schackles and to knock out the pin in pin connectors.(See handle photo).

 

Backside	Tightening handle