TEKNA MICRO Different concept.

[wazu013]

Here I have a Tekna Micro knife. It's 6" long.
The cool thing about this is you push the red button on the end and the blade guard retracts into the handle with a nice spring loaded snap. To reload it you simply pull the guard out until it locks. . I'm not sure what it's use is but I know they made a larger one for under water divers.
check it out.
wazu013

[knife7knut]

The Tekna knives were definitely a different concept.I have a single edge non-serrated version I bought many years ago.I remember there was a bit of a controversy as to whether these could be considered automatic(and therefore illegal in most states)or not.I believe it was finally decided that they were not in the exact context of the law.
The Tekna dive knife did not have a retractable sleeve but instead resembled a boot knife.I have a Japanese knockoff of one;the originals shop up on e-Bay occasionally and are usually pretty pricey.