[blykins]

It's a brand of roller rockers. Instead of using the regular studs that usually hold the shafts down, they use the head fasteners. Very high quality and very stout.

The Ersons are rated for spring pressures of 800 lbs.

If you ever plan to use a solid roller cam with spring pressures over 500 lbs or so, you'll see how factory shafts and hardware hold up.