how is its switch (means how to turn on and off)??
The light is turned on by screwing in the rubber light housing until tight and off by unscrewing until the light goes off.
The light is turned off and on by rotating the head.
You turn on or off by simply screwing the light tight. I have been using for several years. Just untighten until light goes off and tighten to turn light on. I have never have a problem with water leakage. Just do not un tighten too much UW. Good reliable light.
just turn the cap on and off
The light turns on and off by turning the head of the light. I have carried it in my BCD and not turned it on until I needed it and it did not suffer any ill effects.
Personally, I like the idea of a switch, but design works fine.
Turns on and off by rotating the bezel. It isn't quite as positive as a switch. You have to rotate the bezel quite a bit to ensure that the light stays off. Too little rotation and the light goes off, but sometimes comes back on,
The light is switched on and off by rotating the black bezel that holds the lens half a turn
This is a great small pocket dice light I have several
you just turn the top. Impossible to break.
Not so good. It's the standard - twist the bezel - style turn on/off these pencil lights use. It flooded within 20 dives. To be fair, I can't say for sure whether or not I overly loosened it, or the o-ring seal failed. But I have another Princeton Tech light with a twist bezel and it's been going great for 5 years. Always perfectly dry inside.
The light has a screw type on and off switch. The lamp head is screwed until contact is made. The off is simply the reverse. I think it is dependable, once off, it stays off. The same for on.