My eyes aren't what they used to be & I've been having trouble seeing the rear sight notch on my SKS. I wasn't really in the mood to invest in Tech-Sites or similar, so I took a washer with 1/8 inch hole, ground a flat edge, then used the old stand-by (JB Weld ) to fasten washer upright in front of notch in rear sight. Applying some Sharpie finished the job. It works great & if you want take it off, just bust the JB & start over. Might not be for everybody, but works for me.