The improved version. It's been working for 7 years.
The slot must fit well to avoid weakening the chain.
The locking plate keep the hook from falling of if it lays on the bottom (all hooks without positive locks will occasionally come off if they lay in the mud). It also makes the plate stronger with less material. In fact, the hook is proportioned to be full strength with the gate open and one leg detached, but I do not us it that way. Obviously, it could be used from one eye-only, so long as the gate is used and a carabiner clipped through it to secure the gate.
The apex hole is handy for attaching a second rode and anchor.
It can also be made from high strength aluminum, avoiding the need for galvanizing.
I'll post an open-source design when I am finished testing it. It is quite slick in operation. Seadog makes one, but it is too weak, poorly balanced (falls off the chain) and has no lock.
Thinwater, weren't you using a soft shackle on the chain? I've gone to 100% soft shackle use for the snubber. Easy to put on and take off, never falls off, stronger than the snubber, can't jam or damage the chain.