Wayne's Audio Turntable Periphery Stabilizing Outer Ring

If the spindle on your deck is long enough, a center clamp(not weight) along with a rubber washer to dish the LP is a cheap way to flatten not so flat LP's.

I use the screw down clamp, along wth rubber washer on my VPI.

Periphery ring does require a little more attention, to avoid a disaster. 

Weight… only on some turntables will it not be too much mass for motor or suspension. Second, watch out for your stylus, great way to snap it off.

Are outer rings not usable with some very wide-bodied pickups which ride close to the record surface (due to short or non-existent cantilevers)? The Deccas and Londons, for instance.