After buying the Tec Hro risers to find they wiggled under recoil, I bought these 4 days before a Match. I set them for a maximum height. Installed on FWB 2700 Super Match Rifle. Fit on rifle was perfect. I like the spring loaded clamp bolts for quick changes between relays or positions. Only improvement I would suggest is making the spacers from aluminum instead of plastic for longevity and perhaps 5 to 10mm longer rail for more adjustment for eye relief.