I had an E1e-BK do the same to me.
Here you go:
z68 Defender style tritium slotted
FWIW the Lumens Factory tailcaps come with a McClicky switch, which has less resistance and a higher amp rating than the stock Surefire switch, 6A@12V is the highest I have seen claimed, but most say it is a 5A switch. iirc, the Surefire clickies have a 3A current rating, though the twisties are probably much higher.
Also mentioned above:
z68-BK tailcap, also comes in
TN (tan).
Not for nothing, there are three different Backup tailcaps (and I believe not fully compatible with each other, note the thread lengths below), the longer ones are a dual-mode tailcap twisty, I believe... never seen either IRL myself. The missing one looks like the one on the middle left but is as long as the one on the middle right with the collar, but without the collar.