Compatible with the current model Dillon XL-650 RL-550 and Super 1050 (probably a few others too that have the 9/16-18 thread). Ample room in the hook area for those with weighted follower rods too. Installation: No tools required. Remove the primer alarm and the primer tube top nut. Thread this holder onto the primer tube with the hook area up. Thread it all the way on then back a little bit as needed to position it to the side as pictured. Reinstall the primer tube top nut. Due to variances in machines, the top nut may or may not be tight for desired alignment. Reinstall the primer alarm.