It looks like a Harken micro block. Harken quotes a maximum safe working load of 100kg. I guess other manufacturers have similar loads. Add some shockloading to it and it will fail...
Its a 16mm Harken 404 block, SWL is 250-lbs, breaking load is 1200-lbs. I've been using the same set of trap lines for two seasons, what fails is where it connects to the sister clip and the stopper pinches it. That's where I used to luggage tag it on there and have since just started putting in a splice. There's a lot less exposed on the sister clip with just a eye splice there. So far its worked out I have to replace the return part about once a season.
The splices are not stitched or locked otherwise. If unloaded (e.g. if you grab the handle), they can open easily.
They are stitched, I just do it real sneaky like.
(edit)- To each there own on the adjustable setup. I don't care for them, that's why I use the dogbones so you still have a hi/low setting.
