I have a set of the original Leeper Zs and didn't think they could be improved upon. I was wrong. Leeper has outdone himself with the new Z Nailer. It incorporates a sling INTO the piton itself, so instead of using a tie off loop, you clip into the integral sling. This allows the load to be much closer to the rock (and in some cases, actually be inside the crack) than is possible with regular tie offs. Furthermore, clean stacking is also quite easy with the Z Nailers. I give them two thumbs up.