Listing of OTF KNIVES. OTF knives are automatic knives that feature a blade that opens out the front hence the Out The Front (OTF knife) abbreviation. Automatic OTF Front Opening Knives come in two basic categories. There are double action, or dual action, (DA) OTF automatic knives, in which the blade comes out the front via spring power released by the forward motion of a button or ramp. Once the blade comes out the front it locks into place. To retract the blade on a DA OTF Front opening automatic knife the button or ramp is pulled rearward releasing the lock and retracting the blade back into the knife automatically. The other type of OTF front opening automatic knife is the single action (SA). A single action automatic OTF out the front opening knife houses a blade within the chassis that is under constant spring tension. By pressing a button the blade is deployed out the front as on the DA version. The difference is that the blade has to be retracted or "recocked" manually by pressing the release button to unlock the blade then, via a small protrusion on the blade or an internal charging bar, retracted back into the knife handle.Both styles have some of the same advantages. One advantage of a front opening automatic knife is that, unlike a side opening knife, it can feature a double edge. Additionally that blade may have an entirely honed (smooth) edge as well as an entirely serrated edge. IMHO this feature is the best advantage of any front opening knife. Rather than adding serrations to the back of a honed blade the serrations are on top leaving the honed blade for honed blade tasks. The benefit goes further. The serrations up top are out of the way until needed and nearly three times longer than serrations added to the main edge. THIS IS HUGE!! Like carrying two special purpose edges in one compact package. Some just HATE serrations. In my opinion the hatred of serrations is completely negated by having them as a secondary edge for heavy duty cutting tasks WHEN NEEDED. Mindlessly despising serrations and dismissing any knife that has them is myopic. Personally I don't like serrations on a knife with a single edge unless I intend to be encountering some heavy duty cutting task. In that case serrations KICK! Some guys don't like serrations because, they think, they are difficult to resharpen. True dat, if you aren't doing it correctly. I have to admit fouling up more than one blade by trying to resharpen serration with those little files. I've found those files to be largely unnecessary. Most serrated blades need only by touched up by a crock stick or steel ON THE BACK SIDE to re-true up the edge. A person turning up their nose at any knife simply because it has a serrated edge, no matter how much sense or how out of the way until needed the serrations are, is like not buying a 4 wheel drive truck with snow tires because driving in 4 wheel drive uses more fuel and snow tires are noisy. To me that is closed minded. Sure driving in 4 wheel uses more fuel, so use the 2 wheel option until you NEED four wheel drive. It's there when you need it and not when you don't. I understand the tire noise issue. Heavy treads are noisy BUT they sure do come in handy when you find yourself in snow or mud. I wish changing from street tires to snow tires were as easy as turning over my knife to use serrations when I needed them. A serrated top edge on a double edge front opening knife makes absolute perfect and incontrovertible sense.....IMHO.