This "terminal" is simply a tension cable used to secure a length of guardrail and reduce the length of need. It provide no protection to end on impacts and so is typically placed at the downstream end of a guardrail system on divided highways.
Intended Use section for the MGS 31" versions 
The trailing-end anchorage system should be used where needed to anchor downstream end of guardrail [where] (1) end-on impacts will not occur or (2) end terminal is placed outside of clear zone for opposite direction traffic.
There are many non-proprietary versions of this terminal.