Penetration is what you make it. Really if the rod will melt and fuse properly into the top of the material under it, that's all that's needed for a sound weld. If you don't prep the joint correctly to work with the rod you are using, then it's not the rod's fault for not penetrating down that last 1/4". I've used 7014's and run bull dozers over those welds on a trailer everyday when I was younger. It used to be called a "fab" rod, not because it was "fabulous", which it is in the right hands, but because it was the choice of fabricators when they needed to fabricate an item without the use of mig. It's a fast deposit rod and it reduces welding time.