These wads do an excellent job of sealing the gas pressure behind the ridged shot sleeve. In the center of the base, theres a small bump of plastic that directs pressure toward the edges for a complete seal. After a few shots, you can see the ridge lines in the end of the barrel which says the shot column isn't totally collapsing the sidewalls of the sleeve. The Lage wad is the most favored wad I've ever used!
It's too bad the molds for these great wads are sitting idle somewhere in Iowa these days!! Such a shame too!