Some technical info:
Made in Sweden for the deep sea fishing industry.
The 'Stainproof' material is a unique stainless steel with virtually no corrosion properties and the strength of Grade 80 material. Experience shows that Stainproof products have up to 10 times the life in seawater than standard high tensile steel.
The highest Grade of galvanmised anchor chain in the world is AQUA7, a Grade 70. Most boats have either a Grade 30 or a Grade 40. So theese fittings being a Grade 80 means they are considerably stronger then the chains they would go on. The numbers are directly proportional so G80 is twice the strength of a G40.
One ready to assemble showing the retaining pin and retaining lock
Here we see it being attached to the chain
This one shows the HLock being assembled. You put the 2 ends togeather, which you can see only goes one way so you can't get it wrong. Then the retaining pin being pushed through the ends and the retaining lock. This takes little effort but probably will require a gentle tap with a small hammer. The retaining lock has a spring like gizmo inside it which grabs the pin stopping it from coming out. It is possible and OK to do, knock the retaining pin out at a later date, this will again require some gentle tapping by a hammer, it will not just fall out, it can't.
Here we see it assembled ready to go
The same but from the side
And again showing how the HLock can articulate in all directions quite freely.