Sure Snapper,
The E1E and E2E are currently delivered with the lockout tailcaps... LOTC in the threads. It requires a push of the button on the end of the tailcap for momentary on, or you can twist it in to get constant on. To twist back to the normal position, you simply allign the two markers, and you are back at momentary on. Twist one more revolution to the markers, and you are at the lockout position, where the light cannot be accidentally activated, preventing battery drain if the switch is accidently depressed when packed.
The Z57 tailcap is the clickie model. You push lightly for momentary on, push all the way to the click to activate constant on. The clickie can also be locked out with a 360 degree twist out, but is not marked for allignment with the body.
I use both types of tailcaps, and I like them both. Since I usually use momentary on, I rarely think about the difference.
David <><