All new and improved design. When we redesigned these retro-fit hydraulic roller lifters, we wanted the most durable, trouble free lifter available. We did this by using the same materials as our solid roller lifters. And instead of using O.E. style bearing as most other performance units, we used the very same bearings as our solid vertical bar roller lifters. These bearings have endured over twice the pressures of any hydraulic roller application. In other words simply the best.