The SF 9Z "Combat Light" is an earlier "round" version of the Z3. It came standard with the P90 lamp assembly (105 lumens for 60 minutes), but could also use the P91 lamp assembly (200 lumens for 18 minutes). I don't remember when the 9Z was discontinued and replaced with the Z3, but I just read the Z3 was discontinued approximately 6 years ago. The 9Z (along with the Z3) came with the lexan lens and non shock resistant bezel. I guess you could call the 9Z the companion light to the 2 cell 6Z (which was replaced by the current production Z2). I'm fairly certain that the light has some collector's value, but how much I don't know.