I have 2 of them. I have had them for years. They used to sell them at Walmart, but haven't for a long time. One is mounted on my 357 MAX, just ahead of the hammer, like yours. The other one is on a Marlin 1894 (44 Magnum), just above the hammer. They have a long eye relief and hold zero. I know they are not the best for light transmission. However, I have used the 357 MAX at night with a flashlight and 38 Special wadcutters for back yard varmints. I have had them on 22 rimfires and they work good for that application too.
Good Luck and Good Shooting