First, if you have a Chinese SKS, you'll find the TS100 to be too low for a good sight picture. This is, so far as I know, unique to the Chinese type. It was a disappointment, though, as I wanted to use both sight leaves.
The TS200 worked, but I didn't like it as much.
The set screws are made from non-marring metal. The ones on mine were brass. They are tightened down so that the sight doesn't move.
Had I kept the SKS, I would have used those holes to permanently mount the sight on the rear cover.
You'll be required to remove the cover latch. I cut mine in half.
It didn't help my precision with the carbine, but it made it easier to be precise, if that makes sense.
I found that for the ranges I used it, a drilled-out aperture was best. Range was 100 yards and under.
The downside of the sight is that it made the carbine considerably harder to field strip. I've often thought that if a ghost ring were mounted on the rear cover, it would be precise enough (unlike using the cover to mount a 'scope, which just doesn't work well.) Use the front sight to make windage and elevation adjustments.
The Tech-Sight is a good product, and as I'm sure you realize, I'm considerably interested in all sorts of sighting systems.
Thanks Josh. Good to know info before making a purchase. I had figured it would add some difficulty to stripping. The intended weapon is a Russian and I'm not too keen on having to cut off anything but had figured that was likely the case for mounting by looking at the pics. Thanks again for your feedback.