This is a Suncor cheapie bow shackle, basically a knock-off of the very well made Wichard recessed hex head pin shackle. Suncor shackle is about an 1/8 of the cost but is stamped with the stainless steel grade and stock diameter. The main quality difference between the two is the total crap tooling on the Suncor pin including the hex head, pin threads and the receiving threads on the shackle, very poor. So I drilled out the Suncor threads to a perfect slic pin fit and am just using the stainless bow part of it.
There are some subtle details to the finishing work I did on the bow shackle for optimal slic pin functionality. Funny thing is I used a recalled Quickie slic pin with the rounded keeper spring teeth. With the fit I got doesn't matter, won't come out unless you're removing it intentionally. Effectively zero play in the fit.
For sure if you have a tight eye on your main rope and you put a very rope friendly (as opposed to the Quickie which is less so) slic pin bow shackle on the end you have a very sweet and easily configured choking system. Yep, product waiting to happen. You read it here first ;-)
Binoculars are required though, you want to verify everything ended up as you expected it (slic pin end not pressing against wood) when you set the choke. With my double eye setup I discovered the carabiner on the end eye can act as a backup to the shackle. With the very tight eye I've got the biner doesn't rotate position. Very cool benefit, makes your climb that much better when you know you have strength with the shackle and a back up in the mix in case something about the slic pin position goes unobserved after you set the choke.
-AJ